But a much easier argument against sports betting is that it ruins the sports. Players throw. They get good at subtly cheating. The gambling apparatus latches itself to the sport, to the teams and players, the umpires and judges, the sporting organizations. With this much money on the line, it's not a matter of if but when games are thrown, cheated -- the bigger the game, the bigger the incentive. It's even easier now because of the amount of side/parlay betting that is available. It exhausts the spirit of competition.
Sports gambling is diametrically opposed to sport itself.
Ban advertising for gambling, tax the hell out of gambling companies... possibly create some sort of regulation for actual gamblers, i.e. check their ID against a national database everytime they bet to ensure they're not over-doing it... seems more likely to fix the issue than outright prohibition, which, at least for other things like drugs and prostitution, doesn't really seem to solve much.