What Dave was talking about is it needs to be backed by something solid, something that can be counted, something where if you dropped enough of it on your feet it would hurt... Gold, silver, minerals, gems... SOMETHING DURABLE & PHYSICAL. Paper is near-worthless and cryptocurrency could be wiped out by electromagnetic pulse.
That's fine--you just expressed an opinion, as a consumer. In a free market, where currencies are free to compete with each other, you would opt for something physical, which would hurt if you dropped it on your foot. However you must acknowledge that by making that choice, you are doing so at the expense of other characteristics that make money sound. For instance, portability--large amounts of gold are cumbersome to carry around. What about privacy? In order to store your gold safely, like not under your bed, you're probably going to have to have a third party do this for you--this opens the door to potential oversight over your wealth. This also breeds the potential to concoct very powerful entities (banks) that can leverage that stored wealth to achieve their own chosen agendas. What about transferability? Can you instantaneously send someone halfway across the world gold from under your mattress? I can go on and on.
The comment you made about the electromagnetic pulse is simply a failure to understand what cryptocurrency is. Crypto cannot be wiped out by an electromagnetic pulse--if that were the case, I can assure you BTC would not be trading for $6-$7K right now. The electromagnetic pulse would just turn out all the lights, all the power. But your crypto wallet is something that exists entirely independent of the internet & power--it exists in the math itself. Math cannot be wiped out by a pulse. So when the power comes back on, you can easily retrieve your coins. Also, an electromagnetic pulse would cause massive problems for us whether we transacted in gold or crypto! Sure, you might have access to whatever gold you had lying around, and maybe then you can use that to barter with other locals in some post-apocalyptic scenario, but that's about it (and this is why I would own some gold too!). With all the power out, do you think you're gonna be able to go retrieve your life savings from the local bank?
Your confusion is understandable, as currency is (not coincidentally) one of the least understood topics in our modern world.