Since many people try to convince us that Bitcoin is a bubble and how we will lose our money eventually, I wonder if money is not a bubble actually. There exist economies in which money has a positive value in spite its market fundamental is zero. That means fiat money has zero value. Fiat money is a social contrivance. We take money from other people because we know other people will take it from us. In theory and practice the fiat money is a bubble.
Basically, there are three types of real money: commodity, representative, and fiat. The commodity is gold, silver, and copper. the representative is paper money that is backed by gold, 100$ of representative money is equals to 100$ worth of gold. And the fiat, which we are using now is just backed by faith. Basically, the fiat is just literally a paper and has no value at all. So you are right! Fiat is just backed by faith and no real-world value, unlike bitcoin, which is based on supply and demand.
In one way what's been mentioned seems to be the reality of the fiat or the paper money. Same time considering the other part of printing money it is printed with some backing source. With bitcoin we have demand to supply with limitations while with fiat the same but there isn't any limitation. The limitation is set based on the prevailing economic condition.