He probably learned more about business from this venture than $10,000 of business education would have given him. I've also lost that much on a venture once, and the irony is that like his business it was also a potentially profitable and viable business and may have succeeded if we had the experience to approach it differently.
Some of it is not really common sense, because people make these mistakes all the time. I suspect the main mistake he has made, and this happens very often, is that in order to get a decent margin on his product he had to order a fairly large quantity. This broke two things, one not being able to test out the product to determine if that is what the market wants, the other is not to get the hang of all the things that can go wrong with importing goods. I think he was particularly lucky to get it through customs so quickly.
