I'm mystified why technically competent people keep their email in the cloud. Do they never find themselves unable to refer to an email because they are not connected to the web? Isn't obvious that you risk losing everything if the provider goes bankrupt, there is a glitch in their system, or they change the rules?

I use Thunderbird on my laptop precisely so that I have a copy of all my email. I can consult it while offline, I can switch providers, change my mail address, without losing anything and without having to rearrange anything.