edit: like how we've managed to do with literally every single other law?
By that standard, we're done, the matter has already been concluded in favor of "allow gambling."
edit: things can improve, women can open bank accounts without their husband approving it now! We decided something, re-evaluated and made a better decision
Society has already spoken on this matter. It seems that your criteria amount to nothing more than "when I personally dislike the results of the social process, the social process has failed, and we ought to revisit it."
So I ask again the question you've begged: by what formula or philosophy are we to determine when a social decision such as "allow gambling" is bad? Is there anything beyond your personal feelings on a topic that we can turn to as a criterion?
By advocacy and persuasion and some level of agreement through democracy.
>By that standard, we're done
Laws can change, so we're never done.
Society is a never-ending churn of social forces. There will always be a matrix of people who are good and bad and indifferent, who think similar and different to one another. It will never settle.
To answer your question about sports gambling in particular (though you did not ask me): I think the bets on specific things happening in a game are more manipulable and thus damaging to sports in general, as well as to the addictive properties of gambling, than simply betting on an outcome of a game.
So yeah, some aspects of gambling are bad enough that, now that we've seen the impact it's having, we should consider some more guardrails.
Even the college kid libertarian I used to be would say that the government should enforce "an informed consumer": That people should know what mechanisms gambling companies use to entice and addict people.
[edited for tone]
No ongoing rational standards, logic, or objective argumentation is required or even relevant -- just might makes right, anything goes, whoever convinces the most people to agree through sophistic "advocacy" wins?
I suppose that such a system could exist in theory, but it seems to be heavily at odds with the constitutional legal system that the United States uses.
Of course there is logic and standards. Such as my logic that sports betting on individual plays is more conducive to corruption and more numerous than whole-game outcomes, thus more appropriate for regulation.
The constitution was written in the aftermath of a might-makes-right event called a war. Among other things, it puts in place certain rules more protected than others, to add some order to the chaos and protect minoruty interests.