I created 4 reasonably successful companies in my life, and about 12 that fell flat. The first success was in high school. But the first million+ was at age 34. At first I thought the article was a little too academic, but... honestly it fits my life pattern. So... there you have it.
Consider that the vast majority (something like 9/10) of companies fail within 2-3 years. If you're not willing to deal with failures, chances are you'll stop trying long before you get to 12. If you deal with the odds, you keep going as long as you get something out of it
Also, even companies that "fall flat" may be worth it. For my part, a large part of my current salary is down to my experience and contacts from my various startups. And each one of them have been fun for the most part.
