Overbooking means airlines can offer passengers refundable tickets.
Occasionally they get it wrong and have too many people show up. So they offer compensation to get people to voluntarily give up seats. If they can't get people to voluntarily give up seats they have the right to pick who to deny service to (but by law have to pay specific compensation to).
It's a system that works well. It keeps planes as full as possible. It keeps fares as low as possible.
I'm not sure it should change based on one guy who decided he was too important to accept being bumped.