I've made lots of errors as an angel investor , and I try not to beat up on myself when things don't go well. I understand that this is a learning journey, and it's going to take me time to get better.
This is why I analyze my errors systematically, because I don't want to repeat them again.
I have found that I am more likely to make mistakes when I think things are pretty obvious. It's when it seems that the issue seems to be a straight-forward "no-brainer" which just needs common sense to resolve , is when I am most likely to err.