The price of Bitcoin can increase. I know we on this forum here are sure that the price will increase, but if everyone thought that way Bitcoin wouldn't be at $45k today, but somewhere else, perhaps near a million or so. What we know is that the supply of Bitcoin is at least fixed at right below 21 million and rather deflationary because of lost keys. That is guaranteed. Fiat doesn't have that guarantee and hence hoarding fiat is an almost automatic gradual loss to your wealth.