I always have believed that the reason Bobby Riggs (55) lost to Billie Jean King (30) was simple. He bet on her (and made a fortune!).
https://en.wikipedia.org/wiki/Bobby_Riggs#%22Mother's_Day_Massacre%22_and_%22Battle_of_the_Sexes%22
In 1973, Riggs saw an opportunity to both make money and draw attention to the sport of tennis. He came out of retirement to challenge one of the world's greatest female players to a match, claiming that the female game was inferior and that a top female player could not beat him, even at the age of 55. After many failed attempts to lure Billie Jean King, he challenged Margaret Court, 30 years old and the top female player in the world, and they played on May 13, Mother's Day, in Ramona, California. Riggs used his drop shots and lobs to keep Court off balance;[43][44] his easy 6–2, 6–1 victory in less than an hour landed him on the cover of both Sports Illustrated and Time magazine.[44][45] The match was called the "Mother's Day Massacre".[46]
Riggs had originally challenged Billie Jean King, but she had declined, regarding the challenge as a fatuous gimmick. Following Court's loss to Riggs, King decided to accept his challenge,[47][48] and the two met in the Houston Astrodome on prime-time television on Thursday, September 20, in a match billed as The Battle of the Sexes.[6] The oddsmakers and writers favored Riggs;[49] he built an early lead, but King won in straight sets (6–4, 6–3, 6–3) for the $100,000 winner-take-all prize.[7][8]
The ESPN program Outside the Lines[50] made an allegation that Riggs took advantage of the overwhelming odds against King and threw the match to get his debts to the mob erased. The program featured a man who had been silent for 40 years, for reasons of self-protection, who claimed that he had worked at a country club, and there heard several members of the mafia talking about Riggs throwing the match in exchange for cancelling his gambling debt to the mob. The program also stated that Riggs's close friend and estate executor Lornie Kuhle vehemently denied Riggs was ever in debt to the mob or received a payoff from them.
*****
You don't go from waxing the floor with the #1 player to losing to BJK unless something is up.
I thought it was well known Bobby threw the match against Billy Jean the gay crusader?
I watched that match. To this day I am convinced Riggs was paid a large chunk of money to throw that match. Watching him "play," he looked as if he wasn't even trying.
Aftermath & Claims: Opinions are mixed on Reddit regarding later allegations from a 2013 report claiming Riggs threw the match to clear mob debts, but King has firmly maintained that he played to win and did not tank