A pivot is a change in strategy without a change in vision.

This is one of the most important lessons of the scientific method: if you cannot fail, you cannot learn.

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.

Most companies are busy making their products worse, not better. Updating is almost always a disaster.

In my first start-up, I had an initial advertising budget of $5 per day total. That would buy us 100 clicks per day. At $5 per day, marketing people scoffed and said that is too small to matter. But if you think about it, to an engineer, 100 real humans everyday giving your product a try means you can really start improving.

Start-ups make so many mistakes that the challenge to identify the root cause of a failure is tough. But believing in your own plan is probably the worst.

Here in Silicon Valley, I have taken part in hundreds of conversations trying to convince people to dive in and become entrepreneurs. All too often, innovators with good, safe, jobs are unwilling to put their family's access to health care at risk by walking away from company-backed medical insurance.