I don't think the 'gambling' part has a whole lot to do with the failure of pool here in the USA. I don't think most people object to someone placing a wager and taking a risk on their own judgment and confidence about the outcome of an event. Even the most puritanical like to bet a few bucks on a horse race or a football game. Members of the clergy make simple $2 nassaus every day at golf courses. The gambling isn't the issue, in my opinion.
Few here have mentioned the guns, knives, ex-cons, and violence aspects of pool rooms.
Many of the books and stories you read, about pool history, are filled with comments about "me and my pistol", "had to take a shank to him", "his wife shot him at a table", "we've got baseball bats and machine guns here in Chicago", "met him in the parking lot and took back the money", "he was an expert at jarring a mark", "how to air barrel and get away with it", "so and so was the shotcaller in that room like on the yard so when something started jumping off, the others knew what to do", etc. etc. on and on it goes.
By and large, pool room patrons are not even near the mainstream of civilized society.
Parents do not want their youngsters being in such places as they're growing up.
So, the youth are encouraged to take to healthy active outdoor sports which require good exercise and good health.
Sure, there are pool players who're exceptions...but they're far from the usual.
Again...by and large, pool room patrons are not in the mainstream of a civilized society.
And that is a rotten shame, for such a wonderful game that requires so much skill and effort. But realistically speaking.........there is no hope for it.