Depends on what one values
If I owned Facebook I would sell it and do something useful or fun, hopefully both instead.
This isn't to say that Facebook is of no use, far from it, but there are many alternatives for communicating with those one actually cares about that doesn't involve sharing ones most intimate details with an advertising network. Of course if one wants to brag to strangers it is the perfect platform.
Perhaps Mr Zuckerberg is having too much fun running Facebook, perhaps he thinks it is genuinely useful or perhaps the kudos and the dollars keep him at it?
Biting the hand that feeds IT
