Gambling increased because many states recently legalized it. Any other correlation is puff science.
I know more than a few degenerate gamblers. My one buddy bets ~250k/yr, the rest are about ~100k. I'm like 10k (and through luck or skill I end every year up between 2-10k).
I'm the only gamer of this group of 10 people, even as kids.
Their data is lacking to draw strong conclusions, but the question is interesting.