The real problem is that barriers to entry for competition are insurmountable.
If I wanna compete, I gotta host those files somewhere. With Google, Amazon, or Microsoft. That's basically my whole list of options.
I mean, I can opt to do it myself, but... That's beyond David v Goliath. No way I could manage the amount of spam, CSA, DMCA, terrorism/misinformation and other shit that would seek to take the competition out.
The other reason why it's impossible is simply that nobody would upload their genuine content to your site because it doesn't get as much "engagement" as on YouTube. Social inertia is why YouTube can pretty much do whatever the fuck they want and people will stay.
Twitch is the same thing for livestreams. Not even Facebook using fuck-you money to literally buy exclusivity contracts with streamers could change that. People just didn't want to watch there (although I can understand their reluctance).
Your metadata is still extremely valuable to them, and it's not limited to just watch history and likes, but rather everything on how you engage in their services, including where your mouse cursor sits.
Parroting the angry me Yorker whose name I forgot. If you use an ad blocker your likely privacy aware and they don't get much/any meta data from you.
Also YouTube is extremely costly to run. They are making it abundantly clear you are not valuable to them if you aren't watching ads. You aren't that important.
Yes and no. Metadata is more than just tracking info. I did mention watch history, likes, and mouse position, which are not things that can really be blocked. This also includes things such as how likely you are to click on a video based on thumbnail and screen position, how long you watch specific videos as well as how long your overall watch train is. They know what they're showing you, where it is, and what you click and when; that's enough to provide a hell of a lot if data. All in all, how you actually use the service is something that they pay very close attention to, and is still very valuable.
Is it as valuable as tracking info and advertising, definitely not. But it's far from worthless.
Because you aren't an individual to them, you're a statistic providing them with valuable market research on how their service is used.
"People that watch this collection of video classifications are more likely to watch videos who's thumbnails have these characteristics. Only 1% of them use ad blocking so we can improve our ad presentation rate if we present more videos with these thumbnails to this group."
But the value per person they get from " use your data to tailor ads for those around you" a tiny amount and the amount they get from selling your eyeball space directly to paying customers is (comparatively) vast, I could easily see it being 1000x greater or even more. Youtube is going to war on adblockers for a reason.