Good for you, that's the smart way to use e-mail. But most people, many of in tech and many of them knowing better, rely on GMail's web and mobile apps.

Also, unless you're using IMAP to sync the entire mailbox, you'd still lose. If your mail program only stores e.g. last 30 days of mail locally, and lets everything else live on the mailserver, then you'd only have 30 days worth of e-mails left.

This would be assuming that google opted to drop imap with zero warning AND you weren't smart enough to sync all your mail.

The first is out of character for google and the second is totally within your control.

All your mail is for most people merely GB at most per user.