Open Source is great because bad CEOs can't really threaten the source code.

Most of the time this is true, but for browser engines it's different because of their sheer size, complexity, need to adhere and collaborate with others to form web standards, need for security experts, day one vulnerability patches, etc.

If Mozilla dies, LibreWolf can't just pick up the slack. They die too. Volunteers alone can't run a modern web engine, it takes hundreds of millions per year to upkeep.

There's a reason why we're down to just Google, Apple, and Mozilla. Nobody wants to foot that bill unless they have a damn good reason for doing so.

It's probably more expensive to maintain a browser engine than a full operating system at this point.