It's because they are less educated and have less experience than most of us. Any online storage or cloud storage shouldn't be used to keep our private keys. It's never been a good idea to do that. People that will continue to do so, will learn the lesson the hard and expensive way. Hardware wallets aren't cheap if we'll be looking for additional security for our funds. It is considered an investment just like companies that are strengthening their securities to their platforms and assets. So, we should secure our assets too and backups or seed phrases or private keys kept on Google Drive, emails, dropbox, and other cloud platforms is a huge NO.