You don't own your data on a blockchain because everyone running a node gets access to it. Once you publish the data, it's fair game.

Only if the network says so. I assume you are talking about blogging combined with optional tips here. If you were talking about an RPG game you'd for sure own your character and all the items you farmed and everything else, and you'd be able to sell them at a profit without having to worry about tips. You'd get paid the fair market price (better or worse depending on time, supply, and demand).

If I send Bitcoin to someone... everyone gets that information, but all that information says is that I transferred Bitcoin from one person to another.

Ah whatever you know all this already. People do overhype blockchain and act like it's a silver bullet that's going to solve all problems. No argument there.