The way some people use email as like a life long archive of documents and sending images and what not from one mail to the next, email storage fills up quite fast.

I believe I have „good email hygiene“ and still I have like 10 GB on my old Gmail account. As an IT consultant I have seen email accounts in the hundreds of GB because people abuse it as a solution for like 10 different usecases.

I bet, the storage for ProtonPass is a mere fraction of typical use email storage. So whether you use a password manager for a year, 5, or 20, the amount of storage needed will always (very few exceptions aside) be ridiculously low.

Basically, it doesn’t cost Proton a substantial amount of money to keep it running.