The other problem with the ideas guy is that they usually can't see how difficult something is and want it asap. What ends up happening is that they either change their idea mid-stream or move onto something else. If they actually had any time (besides the idea) invested in it, this most likely wouldn't happen.

This is why you should partner up with someone with connections, money, or both if you are developer. Otherwise, they will not bring enough to the table.