Sharma is one of more than 700 drivers in San Francisco who took out large loans to buy medallions, the licenses to operate a cab. But now that Lyft and Uber have decimated the taxi industry, drivers aren't making nearly enough to cover their loan payments.

Sharma has paid $80,000 toward his medallion, nearly a third of the total cost. If he were to default now on the loan, he would lose all of the money he paid in, which would be a devastating blow for him and his family. It's his entire life savings.

A decade ago, San Francisco made tens of millions of dollars selling taxi medallions to drivers for $250,000 a piece. But now the medallion market is frozen — no one has bought one in almost four years.

Because there are no buyers for medallions, those who have one are stuck with it, and they are shackled to the loan payments. So even though there are often so few fares that drivers struggle to make even minimum wage, their only option is to keep driving and driving.

Nearly everyone at the SFO taxi lot had a story of loss and suffering. Some, like Sharma, lost their homes and are renting now.

When Sameh Alshriedeh lost his home, he didn’t have enough money for rent and said he was forced to take his family to a homeless shelter.

For the past three years, Ali Alikhani said he's been using his Social Security money to pay off the medallion loan every month.

The pain can also be physical. Abdelellah Alhimsi said he ground his teeth so hard that he broke the night guard he wore to protect them. He couldn't afford the $500 to replace it, and after breaking the guard, broke five of his teeth, he said.

Another driver, Ali Asghar, said he's been suffering anxiety attacks at night.

“Sometimes I get up early, like nighttime when I’m sleeping, and I am freaked out and all sweaty,” Asghar said. “Then I put my kids in front of me. I say we’re living in America, my kids are suffering. How will be their future?”

Several drivers have died from illnesses commonly related to stress. KQED reported on the story of Edward Agababian who died in his cab at age 59 from a torn aorta. Three weeks ago, Muhamed Tokmic-Muha passed away at his home — he was only 51 years old. Fellow drivers are now trying to help the family raise money for the funeral.

A few months ago, Alikhani said he found another driver dead in a cab. He had apparently been waiting for a fare and had had a heart attack. Alikhani said he can still see his colleague's face, laying dead in the taxi.

San Francisco has made tweaks to the medallion program, but it is not offering to buy them back. New York City, on the other hand, is working on a debt relief program for their drivers.

Alikhani said he hopes San Francisco will do something similar.

“The only thing I am asking is that the city of San Francisco pay me off and buy me out, that’s it,” Alikhani said.

The groundwork for the medallion crisis was laid in 2010, when a budget deficit followed on the heels of a financial recession. Then-Mayor Gavin Newsom directed the city to start selling taxi medallions. Before then, medallions were awarded on a seniority system, and drivers would wait years to get one.

San Francisco turned to a local credit union to finance the medallion sales. The city encouraged the San Francisco Federal Credit Union to issue subprime loans to drivers, many of whom had bad or no credit.

Jon Cohen, a lawyer for the credit union, said it only agreed at the time because the city promised to maintain a viable market for medallions.