Bolivar, you sound angry, and maybe you have had an unusually bad experience. As a long-time resident of a 55-plus community, my reaction on reading your list of nastiness was that it's the exact opposite of my own experience. Maybe this is unfortunately true of some senior communities, but there are probably thousands of such communities by now; how can you generalize about all of them like that?
It's like saying, "How can anyone want to live in a city? There are lots of bad people in cities." Yeah, but...
Bratty kids? We very seldom see kids of any sort around here, and I would put that down as a defect in senior communities. I like kids. Occasionally, on the weekend or holidays, we do see a kid or two, visiting their grandparents. I have never seen a single one acting "bratty."
Here, relatives are not allowed to live with the seniors. That would negate calling it a "senior community." They can come for short visits, that's it. Younger people are usually here for quick visits. I have never heard any visitors make noise of any kind.
Hookers? Drug dealers? You've gotta be kidding. We have a practically nonexistent crime rate. And any hooker hanging around here looking for business would probably starve.
About the bullying (I've never seen it) and general cruelty, I've never seen that either. It might exist here and there, as people are people, and you might find that in any apartment house or gated community, or anyplace else where you get lots of people of any age. I haven't seen any particular "immaturity" either, though some of the oldest people do slide into dementia, and usually end up moving to assisted living, or some other arrangement.
I think your description is ridiculous. And your attitude sounds hostile.