A boot strapped founder has no proven track record, no legit investors to back you up. You have a ton of blind spots, which leads to a lot of mistakes. Because you don't have that backing, and you potentially don't have a venture backable idea, you are a magnet for rejection. But you learn to convert that rejection energy into fuel that lights an unrelenting fire under your ass. Lesson number six, you get really, really good at being focused. A boot strap business cannot survive without quality selling. Great sales is the only way that you show people why they should care about you.