Remember that there are things we don't have any control over in life. You have no control over the success or failure of Firefox because its financial means of survival are controlled by people who are not you (unless you feel like signing up for a VPN).
1. Google's fee for default search (the vast majority of their revenue)
2. Paid Firefox services (Mozilla VPN, MDN Plus, etc)
Remember that there are things we don't have any control over in life. You have no control over the success or failure of Firefox because its financial means of survival are controlled by people who are not you (unless you feel like signing up for a VPN).
My understanding is that the Mozilla Corporation is doing just fine for itself. They even have some financial information published [PDF]: https://assets.mozilla.net/annualreport/2021/mozilla-fdn-202...