I'm also interested in getting an explanation from someone in the business. Assuming that you are not selling something like sex.com but are confined to more modest domains, and that you pay about $10/year per domain. Out of a random group of 500 domains, you need to sell 1/year for $5000 just to break even. Sure, you might hit the jackpot once with someone who really wants that one obscure domain you hold but for most domains you will be lucky to even get one offer in 3 years.