If you're so paranoid, then you use offline or isolated environment for important things.
well, I do that too!
we can say "oh it doesn't matter, someone skilled enough can find bugs in any system or flaws in any protocol and hack in". Maybe, but I don't want to be low hanging fruit even if that's true. I guess it's always a trade-off between security and usability: the most secure computer is a broken one, you can't use it, so an adversary can't abuse it