If Google stopped supporting Firefox today, Bing would still pay to be the default engine. If bing does not pay, Yandex would do.
My point here is Firefox still has 2.71% market share, a lot of search engines operators would pay Firefox good money to be their default engine.
The default search revenue stream is guaranteed as long as they have good amount of users.
But they actively choose to ruin it.
How much do you think Tailcat cost Brave? I know Mozilla must spend more money doing legitimate browser development, but they also spend a whole lot of money doing entirely unrelated things.
If it was less than $65 million, the amount of money Mozilla committed to AI and VC back in 2022, it could have been the money they purchased Tailcat with back in 2021.