Right now many people sell their bitcoin because they want more dollars.  Eventually, I think we won’t “sell” our bitcoin just like now we don’t think of selling our dollars.  We’ll give the plumber our bitcoin for the work he’s done because that is the only currency he’ll accept for his work.  If you want bitcoin you’ll have to earn it by providing goods and services.  If you want goods and services from others, you’re gonna have to spend some of your bitcoin to get it.