No, sorry. I think they are so unpleasant sometimes to people who are trying something. The worst mistake is not to try, so people ought to get some credit for at least attempting something, however mis-guided or potentially unsuccessful. Sometimes the most unlikely business ideas are amazing successes, but that is easy to see with hindsight, not before hand.
But, I need to convince myself of my own inventions/products first. I agree with Robin, that the worst mistake is not to try – but the Dragons do tell it like it is. The business world is competitive and fierce.