Don't give bullshit advice
My experience has been to the contrary: I rarely find people willing to crush entrepreneurs' ideas; instead, most people seem to be quite reluctant to tell others that their ideas are, frankly, terrible. In the end,  people waste money on ideas that are untenable.I once had a old friend bring his bajillion-dollar social networking idea to me -- he liked snakes, and wanted to meet other people who liked snakes, so he wanted to make Facebook but only for people that own snakes. And he'd charge for it! And he'd make millions, because damn it, people love snakes!I understand that almost every idea is derivative, and that I can't really understand the pet-snake market, but should I really say "Gee, buddy, I don't know..." when every brain cell is screaming "tell him to run far away from this!"?