Gambling is not impossible to ban, although it will not be easy such examples of states that have banned it show that it is possible and although illegal activity may arise from the ban this can also be stopped by though rules. If government did not ban activities where some may find a way around it, nothing would be banned at all.  Making an activity more difficult to pursue will still reduce the number of those who take it up. It is not impossible to put effective deterrent steps in place, such as the recent US ban on American banks processing credit card payments to internet gambling sites.