Most successful entrepreneurs have crashed and burned at least once. What is important is that you learn from those mistakes so you don't make them again (mind you, you will make a new set of mistakes). It is helpful if you can learn vicariously from others so that you don't have to make every mistake in the book in order to avoid them in the future. You also need to go back and see what you did right in that failed business. Those things you want to make sure you retain (given the right circumstances).
Thoughts?