That's what they are and have been for like 8 years. It's fine. It would be more productive to put it to good use on the browser. I'm not saying that they shouldn't have tried but... they did for almost a decade and they aren't remotely close to being able to sustain themselves without google. It's not defeatist to say that making up for the 600m$/year might be a bit of an unreachable goal at this point.

Chasing ghosts isn't more sustainable than the money from google. Yes it's a business relationship. but I'm not sure how they aren't completely "vassalized", to use your term, at this point already. It's not a potential problem, if google stops paying they would shutdown in a matter of months.

It's not a bad thing, Firefox as we know it wouldn't exist by now otherwise