Has this ever happened before?
Follow-up questions:
If there becomes 100 trillion wallets in use, do you think finding a wallet with a balance will become common? Is the current private key secure enough to last 10,000+ years?
Is there a way to scale up the security of the generated private keys somehow if needed someday?
If you have a huge volume the just store it on a flask drive or external hard drive that way the hacker will no longer have an access to your bitcoin since it is not connected online. There are many ways on how to store your bitcoins especially for big time holders. If you are just doing your research then you can find many alternatives on how to avoid hacking and some of it are on this forum.