Can confirm this is happening. But the money paid is tiny. Think thousands of dollars, not millions. Not enough to keep the lights on. I would assume they do pretty well from donations.

Never assume anyone does well from donations. That's rarely the case.

Donors get benefits.

Source on this claim? All their torrents are released publicly. Why would "companies with deep pockets" need to pay them?

Because they have an interest in the ongoing work of archiving of new things I guess

For fast access

Paying someone, even a pittance, gives you deniability and a chain of ownership.

Using a torrent of the exact same thing does not.