this! If I could get paid for my regular work in Bitcoin then I would certainly spend it. Buying Bitcoin with fiat then spending it seems strange. Most people are probably hodling.
The problem is as I receiving fiat as a income, I preffer to ged rid of the fiat first because I prefer to keep the currency which I value more - Bitcoin. Obviously there are products like mining rigs where I need Bitcoins only so I have no other choice than to spend Bitcoins instead.
And yes there are fees when buying Bitcoins, so buying Bitcoin with fiat then spending is really not best way imo.