I don't think this is true. I don't know anyone who would have benefited from owning gold or bitcoin in an emergency. However, my hometown once had its only internet exchange catch on fire, and the bank had a multiple-hour queue going around the block to withdraw a maximum of (I think) $300 in cash. I've also loaned money to people whose bank accounts got flagged.

For those reasons I keep a week of cash on hand, not because civilisation might collapse, but as a buffer if my access to the banking system is disrupted.