Aside from the risk of theft/fire etc, you're also running the risk of rampant inflation. You should have a variety of investments in different economies. If $bad_politician gets in and turns the US dollar into the Bolivar, your 10m will be worthless. If you've got 20% invested in other countries you're running a much smaller risk, likewise with investments in other assets
Don't put all your eggs in one basket, don't put all your files on one raid, and don't put all your assets under the mattress.
Don't put all your eggs in one basket, don't put all your files on one raid, and don't put all your assets under the mattress.