Monetary economics is a complex subject. I think what you are mostly missing is the quantity theory of money, and for this I highly recommend this video by Milton Friedman.

The quantity theory of money explains why Bitcoin and other fixed-supply cryptocurrencies are volatile: there is no adjusting the quantity, so the price mostly depends on demand. Prima facie evidence for this is the correlation between Google “Bitcoin” search term count and the price of Bitcoin. When people’s interest in Bitcoin rises, its price also rises. This is because Bitcoin quantity follows a strict schedule. At this time, including all Bitcoins lost in the sum, it wouldn’t surprise me if somebody does research and finds out that Bitcoin quantity in circulation is fairly constant and may even be decreasing.

The price volatility is the thing that prevents most cryptocurrencies from becoming media of exchange. That’s why stablecoins were invented. Tether’s USDT, the first successful stablecoin, has become a medium of exchange, but only in exchanges. There are other stablecoins, and there will be more.