I agree with you in theory, but remember that people frequently do illegal things, just illegally. If we assume that people will in practice gamble whether or not it's legal, I'd rather the gambling not be run by organized crime free from the ability of everyone else to oversee and regulate. That would be the same thing which happened with alcohol during Prohibition and which happens now with the many illegal drugs fueling today's Mexican cartels and US gang networks.
> The only reason why it has suddenly become legal everywhere in the US is because many states have found themselves under mountains of deferred liabilities and are scrambling to raise revenues however they can without raising taxes.
And because of a SCOTUS ruling overturning a federal prohibition on states' ability to legalize sports betting, but otherwise yes.