This time it WILL work! The mantra of the developer.
So is it that difficult to translate the same ethos into business: this time I will make it big! Whether there is any cold, hard, lying involved or whether the person touting for a VC payout truly believes what they are saying - that doesn't matter. A VC would have to be a particular kind of fool to be dragged in by the enthusiasm or "irrational exuberance" (to use a term that described the financial crash) and to simply hand out megabucks because one particular presenter waved their arms about more than another. You'd kinda hope the VC people would know the market, assess the chances of success, weigh the probability of failure and then - cautiously - extend a small seed-corn payment to see if there was any chance of success.
But since the VCs are often playing with other people's money, they probably don't care - and are as guilty of promoting their on successes and masking their own failures as the businesses they finance are.