All money is merely a medium of exchange. As you said, there's utility in facilitating transactions to avoid the convolusions of pure barter, but for that the best option is still crypto. All currencies, whether fiat or otherwise, are faith-based in that they rely on the belief in being used to redeem goods and services with them. Which, again, that faith is simply a social contract. We use whatever everyone else is using. Way back in the early days of paper currency - which were really just claim checks on gold and silver - there was doubt about their trustworthiness too.
