A browser has long been not a saleable product and buying side products is the closest thing you can do to fund its development. Not that it is satisfactory, but if you aren't doing that already then your complaints sound less credible IMO.
The Enterprise™ spends insane money on security products, lots of which are bordeline snake-oil. There's no reason a browser couldn't be part of that, especially considering it's at the front line when it comes to threats and could actually make a real difference.
Electron is also popular and Mozilla could produce a Firefox-based alternative (whose selling points could be performance/memory usage/battery life) and provide commercial support.
Is it going to sustain extravagant salaries & bonuses for the C-suite? Debatable. But it can absolutely be a suitable business paying reasonable salaries.