One thing to consider is that it’s not just hosting a site, it’s all the work they do to do the DRM removal and the repack. That takes time, which might be time they could be using to earn money. So getting some money from their work can help incentivize it.
Hard to say what that actually boils down to for each person, if they’re not releasing any expenses info (site costs, time spent per project, etc). If you’re thinking about donating, I’d think of it more as a “thank you” gift for their work than anything else, and give an amount you wouldn’t miss.