Asserting "private email" is a modern litmus test for someone's technical understanding and capabilities, or lack thereof. Snake oil companies will always hide behind "it's encrypted" and "it's hosted in Switzerland" tropes that mean nothing to anyone who has done a modicum of research. Real privacy is not the result of some product, especially not when its so desperately and obviously shilled.
Why wouldn't I support them ? If i care about privacy I should support companies that care about it too, no?
Proton is not perfect, the android mobile app currently doesn't have conversion view neither contact sync, and the desktop bridge doesn't implement Dav protocol, but its the best out there for people who want to protect their privacy.
And if you care about privacy, you shouldn't be using anything made in Australia.