Yes, I agree, you should generally ignore the naysayers, the ones who say "don't do it", "it'll never happen", "this is going nowhere", etc. However, don't immediately write them off. They may actually have some valid points and they should be considered. Sure, you don't have to halt process on your idea, but it can and should force you to re-analyze everything.

If these naysayers completely stop you from continuing your startup, chances are you're not cut out to run one.