"I also want them to be humble and realistic."

Ironically, this statement is neither humble nor realistic. No one cares about how you'd like them to be. If all entrepreneurs were humble and realistic, we'd still be in the Stone Age. Yea, a lot of wild ideas fail, but the small number of them that succeed usually have a big positive impact. It follows that society is better off with a bunch of crazy, unrealistic entrepreneurs trying to "build the next Facebook".