Don't what? Invest in Gold Bullion. Or don't ask the question.
Investing in gold is dodgy I know. I worked out I'd lose 25% immediately, for the sort of amounts I'd be looking at practically.
But still, if I couldn't get cash out of an ATM, and nobody would accept it if I could, what would be a good idea?
I, myself, favour investing heavily in human capital. But that's another issue.
Or do you mean, don't invest because it's a bad idea for the world economy?