Rev sharing agreements can be quite lucrative for the building owner.
Here's an old example https://www.biggerpockets.com/forums/432/topics/554933-cable...
Get a mobile hotspot. I've been using one (Verizon) practically as my only internet provider for a while now. 5G up and down speeds are totally acceptable for everything I do. And there's nothing an apartment complex can do about it. You can also share your phone's internet with other devices. Obviously the real answer is to not live there! But if you must, it's not an internet death sentence.
Amazingly, those are advertised as "included amenities", as if they were a good thing. I'm sure a large number of people are fine with the idea of a managed internet - or they just don't understand.
Honestly, what's stopping a high rise building from doing an internal GPON/XGS-PON distribution to all the buildings inside?
Do they block you from using your own wired connection too, or just Wi-Fi?
Asking you not to set up your own Wi-Fi actually doesn't seem wholly and completely unreasonable to me? It could plausibly lead to congestion and worse performance for everyone.
It reminds me of my college dorm. Every dorm had an ethernet jack, and there was a communal WiFi network, but we were asked to not create our own WiFi hotspots.