if society consisted of mostly gamblers I would have nothing to lose. especially if the country legalizes gambling. even at offline casinos you can meet and share experiences with other players. not to mention the government which gets income from taxes as you said. Gambling will harm society if it is in the wrong place.
professional gamblers are not those who are always in luck or always in victory when playing. they only understand the right time to bet and continue the game or to stop the game before all the capital runs out.
that kind of control that professional gamblers have. In fact, they can't escape losing in the game.
^ Nobody can expect to win continuously. Even professional gamblers are not winning on a consistent basis. One day they are winning and one day they are losing. On the day they are winning, they tend to try their luck. And whenever they see the first sign of problem are lost, they do not play anymore. That's also what they do when they are losing. If they are losing, they do not start to think that they will make money on that day. They put their ego aside and they stop playing. But most of the people who gamble cannot do that. And it does not matter who is gambling, you always have to control emotions if you wanna survive long run.