Nothing of concern to the greater money system happens. All you've done is transferred value for value. You've exchanged Fiat for crypto and another person has exchanged crypto for Fiat. The exchange platform that you're doing this on may make it seem like your Fiat doesn't exist any more, but in fact while you are stacking SATs the recipient of your Fiat is stacking dollars.

Saw your post on Reddit and thought I would say hi.