People see social media and other things like e-mail and video content as free services.

They just want to join and get on with their lives. Most "normies" don't really care about being served ads or being tracked. If you tell them about the surveillance industry behind the scenes they just shrug and keep scrolling their Insta feeds and clicking their youtube videos. Even people who complain about ads seem to be incapable of action if you suggest they install ad-blocker.

The people who understand or care about the problem are the ones who might donate, but not all of them. It's a subset or an subset.

As Jerry says, the donation economy would not be sustainable if the Fediverse was the size of Facebook. Unfortunately that has more to do with human psyche than actual technical merits of ActivityPub or the Fediverse.