My point (which I'm confident you do understand despite the pedantry) is that the browsers themselves are not profitable without taking into account their effects on the entire ecosystem.

Mozilla doesn't have an ecosystem like Google, Microsoft and Apple do. If they want to stay afloat they have to be profitable with the browser alone. So trying to directly compare that to the "free candy" approach which the others can get away with is unrealistic.

It's like asking why Target and Best Buy can't match the prices of Amazon retail, which has a money fountain named AWS in their backyard that can subsidize their other activities for "ecosystem growth". If Amazon retail had been a separate standalone business which had to succeed on its own for the past decade, it probably would have been run differently.

Can't see the value of Amazon Retail here without going full-in with Prime, and not even then.

Though that may be regional, as I speak from Germany.