Kevin O'Leary

When you're an investor, you can look at the quantitative and qualitative elements of an investment, but there's a third aspect: What you feel in your gut.

I'd rather invest in an entrepreneur who has failed before than one who assumes success from day one.

I have met many entrepreneurs who have the passion and even the work ethic to succeed - but who are so obsessed with an idea that they don't see its obvious flaws. Think about that. If you can't even acknowledge your failures, how can you cut the rope and move on?

Downturns are the best time to start businesses because you develop discipline that's very lean and mean in terms of how to spend money. And those habits serve you very well in good times.