Building a successful startup is very hard, and not just in the "it's a lot of hard work" sense, but also in terms of making good decisions. For the average person who went to college and worked in some other industry/capacity, the good decisions are very counterintuitive.

Most VCs have no idea how to accuratly judge startups based on their core merit, or how to make good decision in startups (though they may think they do), so instead they focus on things like "will this founder be able to hype up this startup and sell the next round so I can mark it up on my books".