I've thinking about purchasing Proton Mail Plus only and just only to have IMAP support, but I've looked all the features that the Proton Unlimited Plan have, and honestly I believe it's worth, but I hate having all the eggs in the same basket.
The features I believe worth the most are the 500GB storage, IMAP support, all the VPN servers with P2P and unlimited SimpleLogin aliases, but when I ask if it is worth the price I mean, the majority of those features I can have them having individually with others services and even at lower price.
As much as I would like to suggest that, I wouldn't because this case would have no backups. I believe Google lost someone's google drive data once but that's extremely rare, that drive setup isn't too reliable, no raid, no backups, all this would probably cost much more than their 5tb subscription. Although, in the long term, it may be worth it.
I simply use Tailscale and a family members router / AP which take SDcards to have a backup of my onsite backup, off site.
And then use Mega + Proton drive for backing up the really important things so things are in three (four if you include my phones photo storage) separate places.
Never again am I falling to disks failing, and paying so much to the cloud peeps kinda irks me especially when they can just shut up shop like UbuntuOne did.