The Denver Broncos are valued at $2.4 billion, making them the 11th-most valuable NFL franchise, according to Forbes.

In 1998, John Elway was given an opportunity to own a substantial piece of that wealth, but, according to ESPN’s Darren Rovell, Elway declined, which turned out to be a costly decision.

Owner Pat Bowlen offered a 10 percent share of Broncos ownership for $15 million. Bowlen, who was tight on cash then, also gave Elway the option to buy another 10 percent of the club by foregoing the $21 million salary Bowlen owed him. Elway would have been named Bowlen’s special assistant as a stepping stone to a promised chief operating officer position.

Using Forbes‘ NFL franchise valuation, that 20 percent stake in the club for $36 million would yield Elway an unrealized capital gain of $444 million.

Elway essentially missed out on $444 million in exchange for $36 million. In hindsight, he’s probably kicking himself for not accepting the offer.

Bowlen offered him the right of first refusal if any other ownership stake was put up for sale to anyone other than a Bowlen family member. The downside risk was essentially non-existent. In years two through five of the deal, Elway would have had the option of re-selling his stake to Bowen for $42 million plus eight percent interest per year.

Elway became the Super Bowl MVP on Jan. 31, 1999 as he led the Broncos to a 34-19 win over the Atlanta Falcons, and thereafter retired from playing football. Before retirement Elway expressed a keen interest in business ownership—in auto dealerships. He bought his first car dealership in 1989. By 1997 he parlayed his string of dealerships into an ownership stake of publicly-traded Republic Industries. It was rebranded as AutoNation and became the country’s largest auto selling group. Elway was bought out by AutoNation for $82.5 million in 2001 in a mostly stock deal.

He used his idle time to spend a month with his father Jack Elway who, as Broncos head pro scout, prepared for that year’s NFL draft. Just before the draft, Elway’s father died of an apparent heart attack on April 15, 2001. Instead of joining the Broncos staff after his father’s death, Elway remained independent of the Broncos. Elway learned the craft of general manager through his co-ownership of the arena football team, Colorado Crush. After the league’s collapsed in 2008, Elway helped to coach his son, Jack, play quarterback for the Cherry Creek High School team in Colorado.

Bowlen’s firing of coach Josh McDaniels on Dec. 6, 2010 changed things. Elway expressed interest in working for Bowlen, except as head coach. By Jan. 5, 2011, Elway was named executive vice president of football operations. Elway ended up in the same spot of having full authority to shape the Broncos, but his pocket book is much lighter by the route that he chose.