A better question to ask is 'why it has meaning'. Money supply has meaning because it's money in circulation. If I print 1000 'Buddy Dollars' and sell one to

A better question to ask is 'why it has meaning'. Money supply has meaning because it's money in circulation. If I print 1000 'Buddy Dollars' and sell one to a friend for $1000, it doesn't really mean that I have $1M in Buddy Dollars. It might be helpful to compare the amount of USD spent on goods and services vs. the amount of Crypto spent on goods and services.