I wouldn't say Google Drive is weak for security.  Because it will completely depend on you. Google Drive service is provided through an email.  When you save something to Google Drive you must have that email and whoever has that email will have access to your driver.  So unfortunately if your email gets hacked everything will be stolen from your drive.  And email hacking is a very common thing that happens many times, so I think it is better not to keep important documents, especially the backup or private keys of any wallet in Google Drive.  You can keep it offline on a paper note or pen drive, it will give you better security.