There are many explanations, but the best and perhaps the most accurate one comes from Joshua Allen who writes,

“If you track hot restaurants or party spots in any city, you already know this. It’s a terrible idea to think that a hot place will always be hot, that it’s hot because of some specific strategy that you can own, or that you can sink even more money into it to make it hotter…managing a social space is way more about being a club promoter than about being a technologist. And sometimes being a good club promoter is knowing when a club needs to be retired.”

Having done that thing in the past - Desiparty.com - I know when Allen is talking about.