What is the main driver for anyone to give away their hard earned weights? What is the catch?

Pissing off Dario, probably?

Or rather capturing the people Anthropic keeps alienating.

The Zuck has (in a different context) said that a few billions wasted are a decent bet (or something along those lines), so I think they're playing extra long games here with no real focus on profit any time soon.

To try to prevent as many people as possible from using one model, that gets all the data, and winner takes all.

spoiling the leaders' profit margins