If you have no real product and you start pitching to customers, your "market validation" can often just be a mirage. This is because people often try to appear kind, helpful, or smart - so they just say hollow things like, "Oh, that sounds like a great idea!"

This kind of feedback does not prove they will actually use your product when you put a real thing in front of them.

Similarly, if you have no real traction and you start pitching VCs, then they will start firing brain farts at you, which can be really distracting. They will say stuff like "oh, this would be better if it was in this other vertical".

Focus on growth before pitching VCs. Particularly if you're a first-time founder and/or you're getting this kind of feedback/objection.

Growth transforms your hypothesis into fact. It will minimize or eliminate debate with well-meaning but misguided investors.

Everything else is academic.