The software can have bugs (it is the case for hardware wallets?).
The data on computers can be stolen via internet / key loggers. Also computers fail sooner or later and you don't know who will have access to your HDD.
Cloud storage .. that's laughable security wise.
I really can't think of safer way than paper wallets. They are cheap, and if you are relatively careful you are super safe.
Obviously spreading wealth over multiple paper wallets is the way to go:
* people will not know how much you own
* you can redeem only parts of your money if you want to
Yeah "you have no every day access to your paper wallets". I know, but do you keep 5k euro cash in your wallet when you go out?