Think about why is a neighbourhood/area ugly, badly kept and dangerous in the first place? While in the same city and often just a few kilometres away you feel like you stepped into a different world? It's because of inequalities. Poor people don't have the means to take better care of their space. Plus poverty begets other social issues, like crime. And this took whole centuries and years for people of the same status to live in the same areas, so if I'm poor chances are all my neighbours also are.
Now of course another factor comes in, which is the state/local government/municipality. Aren't both rich and poor areas under their responsibility? If they fix sidewalks and parks and transportation in the rich area, shouldn't they be doing the same in the poor areas too? That's a huge discussion to have but the reality is they don't. For them, lower income areas do not deserve such investment.
And now we have private investors and tourists. So tourists have discovered that it's cheaper to stay in poor areas when they travel and with the rise of airbnb this became very easy. Because pretty much any apartment was able to host tourists and hotels and such were not their only options. So now a smart person thinks that since this one area attracts tourists, I might as well make a nice shop/cafe there.
And since much of the space has been taken over by tourists and investors, what's there for the locals? If I'm someone who's looking for a place to rent within my budget and all I can find is airbnbs and renovated ones that cost double of what they did last year, where am I going to stay? I'm sure I'd prefer a dirty neighbourhood than having to zero out my bank account in order to live somewhere with a nicer kitchen.
So essentially if you're poor they're telling you that you can't have nice things. You accept that as your reality and try to live your life, but then they tell you that they're also going to kick out of your place cause you don't fit their new aesthetics.