We might be harder to monetize with ads but are we harder to monetize beyond that? I'm a Firefox user and you'll have to pry ublock from my cold, dead hands but I do pay for a bunch of online services.

I think the main problem with Firefox is the tiny user share, not the composition of said share. We need to make Firefox more mainstream and the problem will solve itself. Unfortunately it's an uphill battle, Firefox is not cool anymore.