Good idea. It actually has been implemented already. You are also not very specific IMHO.<p>How do I know that after a million users you won't turn into another Mark Zuckerberg like czar?<p>I'd rather stick with the other attempts: Mastodon, Ello, Diaspora. They all offer good levels of privacy.
I'm concerned that donations would not be enough to pay for moderation of the site when it becomes mainstream and you'd get all kinds of abuse, inappropriate/illegal content, etc.