This is a great question. I'm fairly new to this site, but as I read and explore around I'm finding myself in agreement with Paul Graham. In the How to Apply se

This is a great question. I'm fairly new to this site, but as I read and explore around I'm finding myself in agreement with Paul Graham. In the How to Apply section for funding he explains a key thing he looks at is the founders, because initial ideas can and often do change. I think the optimum mix for a successful project is: competent key people, great idea, and market readiness. If all of these line up optimally I feel the venture will likely end up becoming a billion dollar company (youtube is an example). However, I think of all those the people component is most important, because smart competent people can make a success out of things lacking in other areas, but without competent people even great ideas will likely be bungled and flop (friendster and napster come to mind).