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.
My uncle gambled away a successful business, a beautiful house, his family, his friends. In my early memory he was a giant who carried me in the ocean, flying just above the breaking waves. Later on, when I was in elementary school, he lived with us for a bit. Some time later he lived in his Buick. He died alone and with nothing.
In my mind, we all should not allow a man to do that.
That might be the best solution to gambling. At least in Canada, casinos are very well advertised and glamorized. They're often run by the government, but they still market themselves to attract customers in a way you wouldn't expect of say, a safe opioid consumption site. Their slot machines are just as addictive. Sure, there's lip service paid to preventing gambling addiction, eg a piece of paper on the wall instructing patrons to play responsibly. But if we took the same attitude towards it as we do to tobacco, it might just fade away without all the downsides of prohibition.