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.
I owned an ounce of gold in the past. When I needed some quick cash many of the buyers wouldn't buy it for fear of it being fake. The ones that would buy it wanted to pay less than the spot price. I've never owned it since, but silver coins were a different story. I had 1oz Canadian maple leafs that sold very quickly.
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.