if you think about it, fiat money is under extinction... we use "digital" money more and more. We pay for goods and food via credit / debit cards, we pay our bills via e-banking, we get paid via wire transfer, we barely get the chance to get our hands in real "physical" bills and coins.
But digital money is just fiat in digital form. All of the digits written on your debit card and all the money that you get from wire transfer, all of them can be converted to fiat in no time. It's just much easier to use fiat in digital form, thus, we do so. It's really risky to bring worth of 10k$ in the store since that'll require a briefcase and it'll get the attention of the thieves.
Despite the fact that we're using cash less than before and we're starting to move to a cashless society, people are still not using bitcoins because they were never introduced to it.
I think that this is already too much to think about that a thief can steal a suitcase full of money. Already one such amounts is not in the store. If you go, it is only with a bank card, which is money. Almost Fiat also can be in digital form. But when there is a couple of kupyur in your pocket, it's not too bad. Different cases are in life.