Gambling creates addicts, and addicts are more likely to act in desperation. They might steal, default on debt, or kill themselves and are less productive members of society. I bet societies with lots of addicts are much less likely to thrive because they carry a ton of dead weight. Thus we should ban or at least curb gambling because it hurts us all in general.
We legalized online gambling, the end result is more and earlier addiction and the added tax does not outweigh the societal cost due to loss of jobs, added crime and secondary effects of broken families on monetary, let alone ethical grounds. And they had to change the law to have more bite due to gambling sites mostly ignoring the required checks on addicted and heavy usage players, because profits have to be made. At least they got rid of the insane commercials since that's what most normal people complained about.