Not sure I follow? If two people have a 'rational' bet, then is that legal in your eyes? Surely you can't be saying that irrational actions should be illegal, or that gambling on 'irrational' decisions (however one might even try to define that) should be banned? Or that all gambling should be banned, because there is a chance that some bets might be irrational? None of those viewpoints seem to make any kind of sense, as far as I can see?