As you said, from 1942-48, Lassiter won 300,000 gambling at pool. That's 50,000 a year. Back then, that would have bought you about 40 new cars per year or, if you prefer, a pretty big house every year.
Still, I think it's safe to say that guys like Bucktooth and Jack Cooney won a whole lot more than that. What they did, however, can't be done anymore. Staying under the radar is near impossible in the internet era.
My guess is that the answer is Jack Cooney. That whole "Detroit gang" in the 1980-1995 period may have been the biggest action players of all time,and the stars of the Detroit scene, arguably, were the most successful ever gamblers at pool.
My favorite Jack Cooney story is from the night he was inducted into the one-pocket hall of fame just a few years ago. George Breedlove, a prolific and successful road warrior of pool who'd have been well aware of Cooney, attended Jack's induction. I saw George later that evening and he said to me "I never knew until tonight what he looked like." Now that's under the radar!
No wonder Cooney made so much money. Of course, noone knows how much he made.
