with the danger, that this goes into a (non developper) political discussion or an opinion based thread :-)
bitcoin is a mathematical system running on computers to transfer values in an area, which can be described "unsecure". The design was to be able to transfer values/information, even if there are a lot of bad actors in the game. And you become your own bank. And yes, there is the risk of changes in price, cause it is market based, no instituion or government defines it price.
With FIAT money in the traditional world this is a centralized, controlled (and some people say manipulated) environment. In this world you may have less changes in the value, but it depends how you compare it. Compare the amount of goods for 100 Dollars 10 years ago and today (and compare this to bitcoin!). Or have a look at how you pay taxes, to save the banks. Or especially in the US, how you are a slave of the tax system.
Many people have problems with the idea of carrying a risk, and everyone has a different appetite for risk (in this case of change in value). So depending on this capability, the use case for bitcoin can make sense or not.
The ability to gain autonomy in financials and the possibility to change the world with these new crypto currencies is one of the most sexiest things currently happening. In general the bitcoin value grew over the last 10 years in 100s of percents. I just don't see the risk, but this is my personal flavour :-)