Green’s Dictionary of Slang

a gambler who bets heavily but cannot pay off when he loses.

1956		‘Toney Betts’ Across the Board 222: We don’t want to deal to him. We have word he’s going to take a desperado today. [Ibid.] 314: Desperado – One who bets or borrows with no intention to pay; one certain to become a welcher, it being firmly established in gambling circles that a person who takes a welching chance will welch.
1961		J. Scarne Complete Guide to Gambling 677: Desperado A gambler who bets big with bookmakers and cannot pay off when he loses.