They are ten years in at this point. I think they are doing it right.

Enshitifcation happens when users, advertisers, and investors are all competing for resources. With Proton, the users are the investors and there are no advertisers. Users are paying customers. It won't get enshitified.

I am using their services for a couple years now, and their plan have increased, but not my bill. I still pay the same price as when I subscribed. That's howt you keep customers. Also, they increase storage from time to time.

I think it's because a lot of other companies did the same thing, Google Drive and Dropbox also had these 'do tasks and get more space' promos

My personal issue with the above is privacy issues (mainly dropbox with the automatic opt-in AI thing), so who knows. Maybe it'll be ok

You're right, they're trying to get you into the service so when the price goes up there is inertia and friction to leave.

I think Proton is fine for using as an email for signing up for websites just for the sake of avoiding Gmail, but I wouldn't advise anyone to get fully integrated with their ecosystem for syncing contacts, calendars, files, etc. For people concerned with privacy there's better options.