Barter for what? Serious question. If things get bad, why would I want to trade with you for metal? I'll want to trade and barter for things I can actually use and need. Metal won't be one of things when store shelves are empty.
Ok so you need penicillin and the penicillin guy lives 50 miles form you. In your pure barter system you have to haul 3 100 sacks of wheat to barter for penicillin. Not practical. In a low civilization scenario there will be money and it will be something precious and it might as well be gold.
Because of the expectation that one day things will get "unserious". And because there are others who will also be interested in metals for the same reason. A medium of exchange is necessary (maybe not 'necessary', but so darn useful we'll always have one).
As for gold, it's really more a matter of holding value until things come around. If you need to protect several hundred thousand dollars, anything else is just too heavy.
A case of Scotch would be better for bartering purposes.
And ammo, firewood, water, food, etc., assuming you have more than enough for you and your kinfolk.
I see your point.
Ammo in standard calibers will be traded like money if there’s a currency collapse.
The value of .22lr, 5.56mm, 30-06, 9mm, 7.62mm (NATO, Russian, AK-47) .38/.357 will be quickly established.
Time to buy more. Never owned gold, don’t plan to.
For the same reason you trade with dollars now instead of bartering -- it's more convenient.
I don't agree. If things go badly, after an ugly settling out period, trade will resume. If I want you to do some carpentry for me, and I have vegetables, you may not want enough zucchini to feed an army in return for your week of labor. If other people value silver, you might want the coins I got from 50 people in return for that zucchini, since it is much easier to carry and doesn't spoil. You can then trade a little silver for beef jerky, a little for flour, a little for cheese, etc.
All that junk silver will jump start a transition from barter to a trade economy and help us move out of a Mad Max world or whatever happens in an economic collapse. Gold and silver coins are scarce, and they carry real value if people see them as a convenient way of symbolizing the value of the goods or services they were traded for. Coins as money worked from 3,700 years ago to 100 years ago just like paper money today (but inflation-proof if they are not shaved down or diluted with a higher proportion of base metal).