Along with what has already been said, for the same package deal they offer an email, a vpn, a password manager, drive, and alot more space than the competition (500gig).
they include services such as proton sentinel.
https://proton.me/blog/sentinel-high-security-program
and secure core
https://protonvpn.com/support/secure-core-vpn/
one of the few still allowing port forwarding
https://protonvpn.com/support/port-forwarding/
how to use them in high risk countries
https://protonvpn.com/blog/vpn-servers-high-risk-countries/
development over the years and their dedication to bringing privacy, security, freedom of information to the masses speaks for itself.
Encrypt the planet
canabonzai it once it gets thick enough, if you can keep it in veg