I am a bit skeptical that they don't try to monetize Premium users as well -- I mean invisibly, by selling our viewing history, timing of when we watch stuff etc. But I can't do anything about that and I openly admit all my efforts to block YouTube ads on an iPhone have failed so I eventually gave up and just bought Premium.

And to be fair, I don't regret it, because I have another consideration -- I can easily get some nice Xiaomi phone and root it and install various blockers and alternative YouTube frontends... BUT... my Google account is very valuable, a lot is tied to it and Google has become a bit trigger-happy banning and deleting accounts. So I am not willing to risk it. Hence I paid up.