>b) it drives addicts underground where it's hard to identify and help them

I'm not sure about B, it's pretty easy to identify an addict.

The problem I have with sports gambling is the massive commercialization and advertising. We don't tolerate it for cigarettes, and gambling addictions are much worse than cigarette addictions in terms of financial harm.

Gamblers know where to go, but the purpose of all the advertising is attract new gamblers, preferably the compulsive kind.

Another harm is what it does to the integrity of sports. There are famous cases like the 1919 White Sox and Pete Rose. The people who took part were banned for life for a reason.