The linux foundation gets money because quite a lot of products, companies depend on it. Their servers, their iot devices, etc, etc A lot of the code contributions come from the industries that depend on it not just volunteers or people payed with donations by small time linux lovers.

Nobody directly depends on Mozilla and or features in their product and so nobody will give them money because of that. (you can argue rust trough kubernetes and such is an example of the opposite but despite their big influence and contribution it's not really a mozilla product) Electron has chromium at it's core, CEF apps have chromium at their core, all the other popular alternatives have chromium at their core and google has nice control. Despite that this dominance is ultimately bad for everyone. Google gets too much control over internet standards and their implementation. It is trash. and Mozzila depends on them too for their funding.

I'd say we even risk that they wouldn't get hit with monopoly rulings if Mozilla and firefox dies despite their competition being utterly dependant on and at the mercy of the direction of their product.