Execution is harder than you think.

1. Ideas alone can get funded, but only when pitched by entrepreneurs who have done it before. e.g. the last idea-stage company I invested in was a new crm company pitched by an entrepreneur who had already built a huge successful crm company once before.

2. For the rest of us, you have to show you can execute by building a team, some technology, and demonstrating customer traction.

For any given idea, you have to assume that 10 other people have thought of it, so why are you special?