Money runs gambling. It gets transferred from a point to another. From the poor to the wealthy, from the wealthy to the poor.
Let's first talk about how the poor gives the money to the wealthy.... They allocate a huge part of their money (which isn't a lot in the first place) to gambling thinking that this would be the quick fix to their problems. This is how they give the money to the wealthy in this case the casino owners.
But the money can also go from the wealthy to the poor. If the tax from casinos gets collected by the government and is used effectively, it can help a lot of those in need. The money can be used to improve infrastructure, education, healthcare and etc.
You are obviously talking about the big offline casinos. They are paying taxes, but there's a problem. Do you really believe that online crypto casinos are paying any big gambling taxes? I don't have verified information, but I do believe that most online crypto casinos aren't paying any taxes. Maybe I'm wrong. Somebody must provide valid proof that the casinos are paying taxes.
Yes, gambling is a wealth re-distribution from the working class/middle class to the rich. All industries can be viewed as such wealth re-distribution systems as well. That's how capitalism works. The government helps in balancing the system by imposing higher taxes for the rich and a welfare system for the poor(the problem is the lack of effectiveness in both taxation and welfare).