IMO it’s because most early adopters of Bitcoin don’t want to spend it
We should expect this
If you believe in BTC then you have a dying belief that it will one day have the power to transform your life and make you wealthy
If you spend significant BTC (not just a few sats) then your effectively spending mansions and retirement on coffee and pizzas
BTC reminds us that people are economically incentivized and will always act in their own self interest.
We should expect believers to HODL (most of their BTC)
Personally I’m only willing to spend few dollars worth of BTC
Partly because peer-to-peer onboarding is so difficult