The big question is:
Does the money go to Firefox or to funny projects and (what I consider) insane exec salaries?
So yeah, find me a way to finance Firefox only, and not the funny projects, and to ensure that not a single cent goes to their execs (neither directly nor through some creative accounting, where they reduce engineer salaries to offset the cashflow from this new stream, and pocket the savings), and you have my 10 bucks a month for the next 8 years (and possibly longer, but let's see what they do in 8 years). I won't move the goalposts and I'll make good on my promise.
How do you give an organization money, and ensure that that specific dollar doesn't go to the execs? Any money that goes to the org, pays for those execs one way or another. You can't just ask the Firefox team to pretend they don't exist.