Given that the majority of us believe that Bitcoin will increase in value over time, would u want to spend it rather than hodl and let it appreciate.
Example: Let's say I purchased a car for 1 bitcoin today but next week the value of Bitcoin has doubled meaning I was probably better off using fiat.
No. Bitcoin is not meant to be spent. It is a store of value.
Why would you spend it on something when you can get much more stuff later on for the same amount of coins?
You only spend you FIAT, you hoard your coins. It is as simple as that.