Because they are illegal, most drugs are worth more than gold, by weight. It doesn't matter how nice the neighborhood might be, if the option is to make $400 a week by working your butt off, or $1000 or $4000 a week while getting high all day, it's no surprise that many choose the latter. The problem is that the cops ARE doing something about it. Change the laws and there is no economic driver. The same is true of the Mexican cartels and a lot of the border problems.They mostly go to the public housing projects, I think. Which are located some distance away from the revitalized/gentrified areas. They're not just put out on the street, afaik. They have access to various benefits which enable them to get affordable long-term shelter. And these places could be very nice places to live, with a bit of effort. But, inevitably, the public housing projects become infested with drug-selling violent gangs -- and I suppose that a sort of feeling of resignation and hopelessness overcomes the good people who live there. It's quite sad really. I've seen cities spend millions on making nice places for poor people to live, only to have them degenerate into squalid and physically run down centers of prostitution and drug dealing soon after.
One might ask, gee, why don't the police do something about this? It's a good question, imo. One that I don't have a definitive answer for -- except that I'm pretty sure that it could be prevented.
Anyway, yes, I agree with you -- let's modify some of these idiotic drug laws.
Back when William F Buckley first started pushing the idea of legalization, I thought he was nuts. Then he started to win me over with the economics, States rights, the right of choice, and so on. But only in retrospect do I see that the laws are really the root of much of the drug problem. They prevent constructive, positive, humane solutions that save lives, rather than destroying them and filling the prisons. They are to a highly significant degree what funds and motivates much of the gang violence in the cities. And they are what motivates the gangs to expand into small cities and now rural communities. It's a business. MS-13 probably wouldn't exist today were it not for the war on drugs.