Anything that has any chances of happening no matter how slim is not totally impossible so a gambler that is up for high risks can take a chance and bet. I think that impossible bets should be more on prediction sites where people will bet on things like whether that they're not sure of seeing. Betting on impossible outcomes should be for fun and needless to emphasize that such bets should be with amount that the bettor can afford to loose because the chance of winning will be very slim. Gambling should be about the thrill of taking reasonable risks for reward if the gambler is lucky, it shouldn't be something to take too seriously.