Ideas have value to the extent that they are coupled with excellent execution. One without the other is worthless but combined they have value. Because of this interaction simplistic statements such as "ideas are valuable" or "ideas are worthless" are both incorrect.
The same situation even applies to something more concrete than a simple idea - code. I may have developed a high-quality code base with extensive functionality. However that code has little if any value in and of itself, unless I can apply it to solving a problem that people actually have and are willing to pay for.