Can someone help me understand the problems with gentrification? Do renters feel entitled to stay in their neighborhoods even when their leases end? When owners

Can someone help me understand the problems with gentrification? Do renters feel entitled to stay in their neighborhoods even when their leases end? When owners need to perform remodels on [unoccupied] aging homes? The only real issue that comes to mind is the owner of a home on a fixed income having to pay higher property taxes because the area around them is improving. I can think of lots of ways to mitigate this problem ... but I'm asking about other problems of which I know nothing.