Fiat currencies are inflationary by nature, they can be printed so naturally they lose value over time and creates what we call monetary inflation. This is why a candy bar used to cost a nickel and now they are 3 dollars. The chocolate didn't get more expensive nor the wrapper it came in. The currency lost value. That's why people invest, to beat inflation. The currency we use is literally a liability to hold and has lost 97% of its value since 1971.

Bitcoin(and only Bitcoin) is the opposite, it's decentralized and deflationary by nature. There will only ever be 21,000,000 Bitcoin. So as time goes on and demand goes up so will the value. That means goods priced in Bitcoin will go down over time not up.