Aside from the slot machines in Kanto, Hoenn, and Sinnoh (idk about Unova, I haven't played through that one yet), the original game at least already promotes "gambling". You get money when you win, you lose a couple dollars when you lose. The only difference between what I'm proposing and the real game is that I'm calling it what it is.. or at least what I choose to see it as.. betting money.
I do agree with the first part though, this can be easily be abused but there could probably be a max betting option to prevent winning TOO much money.