You do realize that there's literally no situation where bitcoin is not exchanged back to fiat, right? – Not one. Single. Exchange.
1. Buy gift cards --> They instantly get exchanged to stablecoins & fiat.
2. Pay 10€ (~13000 sats) at a conference peer-to-peer for some bitcoin merch --> That guy is going to pay their print provider in Fiat.
3. Pay 10000 sats for some hand-drawn pencil art --> That guy is going to go back home that evening, sell bitcoin, to buy himself dinner in Fiat.
Next time you take a bite out of your sandwich, think about how you're keeping the fiat system alive by having sold purchasing power into fiat to survive.