Yup; Google / Chrome, Apple / Safari + webkit, and Microsoft / Edge get away with it because their browser is not their product, it's an extra. For Google its original intent was to make the internet faster so that people would see more ads.

Firefox needs a company behind it whose income is not tied to the browser. I don't believe you can monetize a browser, not without doing some dodgy shit like forcing search engines on people, injecting ads, premium features, etc.

I know Firefox tried to launch a number of products over the years to try and make money, but at this point it doesn't seem to be working. I think their only hope financially is to be bought up by a FAANG, but they either have their own browsers or no interest in having one.