Many do! Go to a meetup/event with more than 10 plebs and you'll find one for sure

Wouldn't a true pleb want to bring someone to the light? Sell some sats for cash knowing they will buy more at some point

People who need cash for whatever reason but either A) don't have it, or B) don't want to sell bitcoin via exchange and interact with banks would want your fiat

They can often sell at a spread above kyc, meaning there's arbitrage. As long as they can manage the risk of being targeted they're compensated for their service. Particularly good for miners though not publicly traded ones I would assume.