You should be loyal to people, they might also be afraid to show their interest in the stuff you like. But don't stick to them "no matter what". That can bring you into dark places.
Enforcing boundaries helps, talking about things helps, but sucking it up and abandoning people seemingly willy-nilly will leave you alone and angsty pretty fast. So will just taking everything from an asshole.
I don't have an answer to finding friends yet. Try going to social stuff about the things you like. If you have stuff you deliberately hide then try not to go to those things first, as the shame might make you lash out at potential friends. Wait till you can come to terms with yourself.
It is not tuned for what people want to watch, but to what youtube thinks you want to watch. Also what they think they can get away with suggesting you. My experience is that I do not like what the autoplay function plays next, for example.
There are indeed "backroom bosses" deciding what arbitrary hoops someone has to jump through, youtube is no lawless place. There are enforced rules as to language and video material. This has little to do with the suggestions, but not nothing.
It does a selection that give youtube the most money. That indeed filters out unpopular things (making it also way harder to gain popularity if relying solely on youtube; a widely accepted alternative would be a deal with a popular youtuber), but also controversial stuff like criticism. Also child porn so its not entirely bad (also it is very necessary), just way too powerful and obtuse to be trusted in the hands of someone wanting to make money.