There is no 100% security even in technical terms because every now and then, an exploit is created to breach such security.  Aside from that personal negligence is one great factor why security degrades.  We all know that a fix comes only after an exploit, and an exploit is done when there are security lapses.

Even internet security providers cannot claim 100% security because there is always a malicious file somewhere on the internet that is lurking to hack or hijack our system.

I highly agree that since there is no perfect security we should try to get close as much as possible.  Like applying multiple layers of security to our pc system where we insert our hardware wallet and having the back up file encrypted with a very good password so that hackers will have difficulty in decoding them.