Re: Honest question...
You print out the username and password (plus any emergency 2FA codes) of your email account(s) and stash it somewhere safe, that way you can generally bootstrap your recovery using "Reset my Password" links on websites.
You may want other important accounts saved in the same way.
FWIW I use 1Password... if you really want to move elsewhere it is possible to export everything to a text file if you need to. It does pose a risk in terms of being a single target but, on balance, it allows me to easily have a unique password for every single site (as well as unique email - as was mentioned earlier using + addressing/sub-domaining).