If you read the internal PDF, it's very clear that they reduce money spent for developers and increase money to get end-users.

It's explicitly written as their "step 1".

I don't envy Firefox here... despite being fan-favorite of nerds, it is just about 9% on desktop and declining, while <1% on mobile.

In total, it is less than 1 percentage point more popular than Samsung Internet (the weird bundled Chrome thing on Samsung, with 3 percents).