Every provider out there encrypts mail at rest. You're exchanging emails with Gmail, Yahoo or Hotmail anyway. Pretending like your email is any safer with Proton or clones is a waste of money imho.
That's actually really expensive. 2GB is not a lot unless you're starting from scratch. My 50gb account would cost me ~15€/mo with aliases and extra storage fees.
But most importantly they don't support bringing your own domains which makes it a non-starter for most people looking for custom email solution.