Most great people don't appreciate how valuable they really are. If they did, then lots more of them would be getting million-dollar bonuses. I don't want to overestimate the power of money. He or she didn't support me, didn't communicate with me. It's embarrassing to be around them.
Money usually comes in as the fourth or fifth most common reason.
Understanding why great people leave a company has obvious implications for persuading them to join yours. Your job is to wow them with opportunities for growth, for freedom, for impact. Companies need people who will contribute in the future. That's why some companies have stopped relying on traditional interviews. Interviews aren't good predictors of future performance.