Power, water, internet, healthcare, education, transit, there’s a lot of things that should be public utilities or at least with a convincing public option because of the clear conflict of interest between private corporations and social benefit, but aren’t, because money controls politics.
I see that as offering services that people clearly use and value, and that the bills have to be paid somehow. So as long as proton can deliver the privacy and security features it promises, I personally don’t see anything wrong with providing an alternative when the only other options are built on monetizing your data.