Incidentally, Zuckerberg wasn't scratching his own itch; he took the idea of some other students who's site he was supposedly was helping them to build, and ran with/stole/took 'inspiration from' (depending on your point of view) the idea himself.
>>....he felt he could do a better job than ConnectU and was compelled to do so
If you are aware of the background to the story, it seems like he gave the impression to two fellow Harvard students that he would help them build an internal dating site for Harvard, but some time into the project he decided to stop communicating with them and used the code for what would eventually become Facebook.
http://www.businessinsider.com/how-mark-zuckerberg-hacked-in...
http://bits.blogs.nytimes.com/2008/06/26/judge-ends-facebook...
It's quite a Microsoft-esque tatic I think, i.e. of questionable morals, but potentially a great business move.