I just want to start by holding my own data. (While you my be right that big providers allow to wipe your mails, they can make copies). I just don't want for a third party to relay my data in the first place.
While your points are right there are solutions, and in the long run it's worth it
More than that. Big companies have big backups. Once a piece of information leaves localhost it is logged somewhere permanently. Even if you go and purge all your email now, Google is not going to spool up tape backups and erase all copies.
While your points are right there are solutions, and in the long run it's worth it