The odds of you losing the master data at the same time as being locked out of your account are astronomically low, and if they don't coincide, then you're not

The odds of you losing the master data at the same time as being locked out of your account are astronomically low, and if they don't coincide, then you're not in any trouble (e.g. if you get locked out of your account, then you immediately make another backup e.g. on a USB, and if your main copy has something happen to it, you immediately restore). I definitely agree that getting locked out of your Google account is a massive risk in general (as well as morally bankrupt on their part), but I don't think it's a problem for the specific case of backups).