Dr. Tom Addison, a retired critical-care physician for Kaiser, was never so thrilled to take a financial bath.

Addison and his family were longtime 49ers fans who bought four $5,000 seat licenses for Levi’s Stadium, a one-time $20,000 investment that allowed them to buy four season tickets every year, for $1,250 apiece, at the team’s new Santa Clara stadium. It seemed like money well spent.

The 49ers, under head coach Jim Harbaugh, had become a perennial beast in the National Football League and played in a Super Bowl as the stadium was being built.

Then, the once-gleaming franchise deteriorated in a hurry.

With Harbaugh forced out, the team nosediving on the field, and the new stadium beset by issues of logistics and comfort, Addison wanted out after the 2015 season. He wanted to sell what the team called his Stadium Builder Licenses so he did not have to keep spending $5,000 annually for four season tickets in the corner of an end zone, a requirement to maintain the licenses.

He was able to sell all four on the secondary market, but at $2,000 apiece after dropping his asking price, and recouped only $8,000 of the original $20,000 investment. The alternative would have been walking away from the licenses and getting none of the money back.

“I was relieved to get rid of them,” Addison said in the dining room of his Burlingame home. “I was so happy when the guy wanted to buy all four. I was happy to get out.”

Addison’s story is not unique. Other fans and ticket brokers who bought licenses — costing from $2,000 to $80,000 apiece, depending on seat location — have tried to sell, only to find them tough to move as the 49ers have tanked since they were 12-4 in 2013, their final season at Candlestick Park.

The team went 8-8 in 2014, its inaugural season at Levi’s and Harbaugh’s final year as coach, 5-11 last season and 1-9 thus far in 2016 going into Sunday’s game against the Miami Dolphins.

The 49ers say their numbers suggest Addison’s story is an exception rather than the rule, but there is ample evidence of buyer’s remorse among fans, corporations and ticket brokers who together paid $553 million through the sale of more than 60,000 seat licenses to help defray the $1.2 billion cost of building Levi’s Stadium.

Greg Carl, managing partner of PSLsource, an independent resale site, said the values of 49ers seat licenses have declined with the team’s fortunes. In 2014, Levi’s first year, they were selling at an average of 25 percent above face value, Carl said. Now they are selling at 40 percent below for a simple economic reason.

“Supply on the market has definitely gone way up,” he said. His website lists 1,300 49ers seat licenses for sale.

Moreover, the Santa Clara Stadium Authority, the government entity that sold the licenses, has reported an increase in the default rate among those who financed their licenses, as opposed to paying all the money up front.

The authority said the default rate has risen from 2 percent in 2015 to 6 percent in 2016.

The 49ers tell a much different story. They maintain an official site for reselling seat licenses that on Wednesday had 1,099 listings for 2,784 seats. Although many are listed below face value, the 49ers say that 80 percent of the licenses that were sold on their site since 2014 went for a price that allowed the owners to recoup their investments, principal and interest, or make a profit. The other 20 percent sold below face value.

The team also notes that the licenses currently for sale and the total that have changed hands, 2,400, represent a fraction of the 62,000 currently held by fans and brokers.

“Our fans have been very passionate,” team President Al Guido said in an interview with The Chronicle. “Do they let us know when they’re not happy with the team’s performance? Yes. But we’re not seeing it manifest itself in some mass walkaway from the franchise.”

That might be true, but the lack of action on the resale market could be a product of depressed license values.

“There is so little demand, brokers are getting killed with the investments they have,” Carl said. “They’re totally gun-shy about buying in at discount prices.”

About half the sellers on PSL Source are ticket brokers who invested in the licenses hoping to profit by reselling the season tickets at a premium.

While ordinary fans hardly weep for brokers, whom they consider legal scalpers and profiteers, the market makes no distinction between brokers and die-hard fans who bought the seat licenses.

All paid the same prices for their licenses. All are required to buy season tickets annually or forfeit the licenses. All face the same supply-and-demand imbalance when they try to sell tickets for nonenticing games to help recoup the cost of their investments.

Guido pointed toward the cyclical nature of sports and said tens of thousands of fans who bought seat licenses for Levi’s Stadium also maintained season tickets at Candlestick during lean years after the 49ers won five Super Bowls from 1982-95. The 49ers believe many of those fans, who now have season tickets for Levi’s, are demonstrating the same patience and are not concerned with resale value.

“We were once good, and we know we’re going to be back there,” Guido said. “Ultimately, they bought these (licenses) for the long haul of the building. All of these people knew when they entered into these contracts this was for the life of the stadium.”

The stadium authority reports there are 62,031 active seat licenses, or 94 percent of the 65,877 seats at Levi’s that are deemed available for license purchase. The team lists football capacity at 68,500.

The 49ers did not directly reap the $553 million spent on seat licenses. That went directly to the stadium authority for construction costs. But the 49ers each year get the money from the season tickets that the license holders must buy.

More than half the original buyers financed their licenses through the stadium authority at 8.5 percent interest over 10 years and must make payments each March. The authority reported this week than in 2016 it has failed to collect $2 million of the $30.9 million it billed, a 6 percent default rate.

In 2015, the first year installments were due, the default rate was 2 percent, but the stadium authority said it recouped that money by selling new licenses.

Joel Camarda, a semiretired engineer from San Francisco, did not finance his seat licenses. He paid $12,000 in full for two end-zone seats and does not want to sell because he likes going to most games. That does not mean he is a satisfied customer.

Camarda expressed anger at what he and other fans perceive as mismanagement on the field and in the ownership suite, starting with the decision to remove Harbaugh after Levi’s first season and promote assistant Jim Tomsula to be head coach. Tomsula lasted one 5-11 season and was replaced this year by former Philadelphia Eagles head coach Chip Kelly. The 49ers won their season opener, but have lost all nine games since.

Camarda decried the “ineptitude of ownership,” which he contends has devalued seats that he bought when the team was great.

“They went through so many coaches before Harbaugh,” he said. “Then they hired him and had instant success. They wouldn’t have sold all those seat licenses if not for Harbaugh. Then they undermined him and fired him.”

Camarda said he has tried to resell some of his $125-per-game season tickets, particularly for night games he does not like to attend, and found he often cannot get face value.

Addison said on-field performance factored into his family’s decision to sell their four SBLs, specifically their sense it would not improve soon and their investment would deteriorate further.

“All of a sudden I started thinking, ‘This thing is going down the tubes,’” he said, “‘and if we’re going to get rid of them, we better get rid of them soon, because this is going to be a rough few years.’”

Addison said other factors in selling were the commute to Santa Clara and the discomfort of sitting in the sun, a major complaint by fans on the east side of the stadium.

“I thought we were wusses because people go to (college) games in Alabama and Florida, but the sun was unbearable,” he said. “Even the Roman Colosseum had sun visors.”

The oppressive sun is one reason the stands on the east side of Levi’s often look empty. Many fans with higher-priced seats retreat to an indoor club. Others stand in the concourses in the shade.

Levi’s Stadium opened with other issues, as all stadiums do, including unbearable traffic jams and slow concession lines. The stadium’s reputation for fan unfriendliness could be affecting the resale value of tickets and seat licenses.

Guido acknowledged the 49ers cannot do anything about the sun besides playing August exhibition games at night. The league sets start times for regular-season and playoff games. But he said the team has addressed other issues, and season-ticket holders report in weekly surveys they are happy with the overall stadium experience.

The 49ers say more than 90 percent of fans who buy tickets go through the turnstiles, belying the visual of thousands of empty seats.

The 49ers also must fight the perception that they need not worry about the fan experience or on-field success because the seat licenses force owners to buy season tickets into perpetuity.

Guido said that is not so, because eventually fans will walk away from their licenses or stop attending games if the 49ers do not make Levi’s a fun and comfortable destination, and if they continue to lose.

“We’re working our tails off to get better on and off the field every single day,” Guido said. “That’s why we poll our season ticket holders after every game, why we respond to surveys every single game.

“We know on the business side of the operation we can get better. We’ve proven that. We think our coach and GM will tell you we’re trying everything we can to get better on the field, and I think our fans will ultimately see that and our renewal rates will show it.”

Asked what 49ers representatives tell disgruntled season-ticket holders when they complain, Guido said they note how quickly NFL teams can rise from the ashes and reach the playoffs.

Beyond that, he said, “We try to remind them of that feeling of when they bought, and why they did, and what it means to their families.”

Henry Schulman is a San Francisco Chronicle staff writer. Email: hschulman@sfchronicle.com Twitter: @HankSchulman

How 49ers Stadium Builder Licenses work

In 2014, the 49ers moved from Candlestick Park in San Francisco to Levi’s Stadium in Santa Clara, which cost $1.2 billion to build.

The Santa Clara Stadium Authority, created in a vote of city residents, contributed $879 million toward the construction costs. Part of that came from the sale of more than 60,000 Stadium Builder Licenses to fans, corporations and brokers for a total of $553 million, not including interest paid by buyers who financed the licenses rather than pay everything up front.

The licenses were sold for a one-time cost of $2,000 to $80,000, depending on seat location. Each license enables the holder to buy one season ticket from the 49ers at a price set by the team. As an example, Dr. Tom Addison of Burlingame bought four $5,000 seat licenses for $20,000. He then was required to buy four $1,250 season tickets each year.

The licenses are good for the life of the stadium and can be resold or transferred. The holders are required to buy 49ers season tickets each year. If they don’t, they lose the licenses and the money they spent to buy them. Those who still owe money on licenses and walk away technically expose themselves to lawsuits, although the stadium authority has not filed any.

Dr. Addison resold his four licenses for $2,000 each, or 40 percent of what he paid.

The license holders also get first crack at tickets for non-49ers events at Levi’s Stadium, such as concerts, soccer games and the annual Pac-12 championship football game. The 49ers say that adds value to the licenses. The stadium has hosted 32 such events.