Vanity metrics are the numbers you want to publish on TechCrunch to make your competitors feel bad.

A head start is rarely large enough to matter, and time spent in stealth mode-away from customers-is unlikely to provide a head start. The only way to win is to learn faster than anyone else.

Nowadays people talk about PayPal's founders as prescient geniuses who would inevitably change the world. It was, however, not so obvious that PayPal would taste its first major success by helping people sell Beanie Babies on eBay. But they had a vision, a hope, and the perseverance to try multiple iterations until they got it right.

If your goal is to make money, becoming an entrepreneur is a sucker's bet. Sure, some entrepreneurs make a lot of money, but if you calculate the amount of stress-inducing work and time it takes and multiply that by the low likelihood of success and eventual payoff, it is not a great way to get rich.

The attributes for entrepreneurs cut both ways. You need the ability to ignore inconvenient facts and see the world as it should be and not as it is. This inspires people to take huge leaps of faith. But this blindness to facts can be a liability, too. The characteristics that help entrepreneurs succeed can also lead to their failure.

Most start-up companies fail and it is smart public policy to help entrepreneurs increase their odds of succeeding. But, the biggest loss to our economy is not all the start-ups that didn't make it: It's the ones that might have been created but weren't.

The big question of our time is not Can it be built? but Should it be built? This places us in an unusual historical moment: our future prosperity depends on the quality of our collective imaginations.