They're building a solid thing. I wish they had a geographically spread servers system and you could choose your Proton cloud/drive to be located in different continent for example.
Discussion
Yes I guess that's a bit of a risk but I do most 'cloud' stuff via my own Nextcloud set up. However, given the Proton is there and e2e I might start making more use of it... Completely overhauling my server on Thursday.
Thinking about it, it probably makes sense to backup my Nextcloud to Proton, then there's redundancy.