You build on failure. You use it as a stepping stone. Close the door on the past. You don't try to forget the mistakes, but you don't dwell on it. You don't let it have any of your energy, or any of your time, or any of your space.
“They will come to learn in the end, at their own expense, that it is better to endure competition for rich customers than to be invested with monopoly over impoverished customers.”