Beyond that however I agree that turning this loose on the American public is an incredibly short-sighted act, but it's part of a pattern rather than an outlier.
So rationality? You're assuming there's good options available for these people. But if they don't own a home ... they won't lose much, and their careers provide them with little to gain month to month.
Isn't it rational under those circumstances to try to get quick large reward ... or fail entirely? When you have no real other options and even arguably little to lose?
The time when being a non-educated worker in a big city would get you a house, a family, and pretty good comfort, enabling ordering 5 beers most evenings in a pub, have a hobby, ... has long ended, at least in Australia.
The fact that you can go into any neighborhood dive bar and see a bunch of nearly indigent drunks doesn't mean that people aren't drinking themselves to death in mansions, private clubs, or $1000 a meal restaurants.
As for rational risk, most people consider the line between having enough for daily expenses, making debt payments, and having a place to rent is a massive upgrade over a shelter or the streets. Or working a second job, or a third.
The stereotypical problem gambler in Australia is a lonely retiree blowing their pension at the pokies (slots), and clubs and casinos go all out to cater to this demographic with free taxi services etc.