I just turned 40 this year. I have 7 failed businesses behind me and one that is still alive, doing well.<p>One thing I have noticed is that a better understanding of how the world ACTUALLY works has been a huge help in avoiding the many pitfalls that await the intrepid explorer. And since there is no manual that explains all of this, you can only really get it through hard experience. And to make matters worse, once it's internalized, it just becomes part of your background thought process, making it difficult to explain to others because you hardly even notice it's there until you see someone about to make a huge mistake.