Mozilla's main source of revenue has always been the money Google gives them to have Google as the default search engine. They could stop this at any time to effectively kill Mozilla. So, why haven't they? Because there's this case called United States v. Microsoft Corporation that deals with this very issue of browser monopolies. Now usually a lawsuit wouldn't mean dick to Google because they already have a litany of lawsuits against them that their star legal team is hired to handle. But in this one narrow instance a precedent case is massive, and were Google to kill Mozilla, there would be a league of lawyers jumping over themselves to sue Google on this. Why? Because it's a slam dunk, and would at best force Google to say "hey, you can download Chrome, or you can use these alternative browsers" everywhere there's a Chrome download prompt, or at worst force them to split up. They don't want that.

Regarding Mozilla's direction, we already have years of evidence. It all starts with Brendan Eich's resigning. Whether you agree the reasoning is immaterial; that decision lead him to start a direct competitor that is now fighting them for the ever-shrinking demographic of people that don't use Chrome. And then there's stuff like acquiring Pocket, something completely antithetical to Firefox's core values. Money-wasters like FoxOS (or whatever that mobile OS was called) that distracted from Firefox. And then lots of tick-tacky stuff like FF devtools being inferior to Chrome for years (people say it's better now, but I don't care to check it out, I've been using Chrome's for years), over-focusing on frivolous things like social justice issues. It will be death by 1000 cuts that kills Mozilla from the inside.