It's true that Mozilla gets the vast majority of their income from Google and has, IMO absolutely squandered most of it.

If Mozilla had put most of its income into an endowment fund instead of hiring tons of staff for a miriad of now-mostly-canceled projects, they'd be in a much better position today. (Hindsight is 20-20 and all that.)

But I think it's an overstatement to say that Google owns Firefox. I donate monthly, and I think a smaller form of Mozilla could survive completely without Google.