Complete ban on gambling is a tricky thing as it's not always a straight-forward thing to determine what is or isn't gambling.
Best example could be poker. In many countries it would fall under definition of gambling, whereas in others, it's considered to be a skill game.
Or even things like UK's premium bonds, where instead of fixed interest every bond is a lottery ticket, where you could potentially win a lot of money, but per statistical chances, the expected win is in line with the "normal" bonds, and you don't really lose the amount deposited.