You dont know how the sender or recipient handles your mail, but handling your own with encryption is still a good practice.
An email provider can have an entire database of all your emails (e.g. Google with Gmail), which more valuable than individual people or companies having access to only a few related ones.
There's also PGP support with some providers, so you could set-up encrypted emailing with people if that's important to you.
Either way, getting away from the big providers is a good move, I'd at least want my inbox encrypted though, like Proton or others do.
Fully encrypted email should have been made standard a long time ago.
The teams will still all go. It's all corrupt.