reality is, sometimes entrepreneurs have to try lots of businesses before finally getting the real one that works. its what determines the difference between a successful one and the not so successful. Not all entrepreneurs take chances by making "spaghetti on the wall" decisions - seeing if they will work or not.
Even when businesses are calculated and deliberated upon. They sometimes fail even then, because of factors beyond control. What I know is that the experience accumulates into a deal/business that you can call "your life's work". Pretty much like Handel's Messiah.
its your ability to pick yourself up. and once you try and try, that experience, is what you use to succeed in your final venture
You cant get a top job without experience. Failure to entrepreneur is what working experience is for those who work for others. No short cuts to the top.
(only risk and thrill chasers get this, besides, losing everything or having to start from scratch in life should not be feared. Steve Jobs sold his mother's house "to go and find himself" in the east somewhere (in Bali or something) - the rest as we all know is history.