You only have to be right a few times in your life to make your career. Most people are right zero times, and hardly anyone is right 10 times. Von Neumann might have hit 10.
So regretting past mistakes is a big waste of time. Learn from them, but don't let it get to you emotionally. (All easy advice to give, and hard to follow.)
But then they’d have to own up to the nauseating idea of callously dismissing some truly spectacular sea changes, such as failing to buy 1000 Bitcoins for a few dollars in 2009. I think most people are too full of envy to do that.
How many can honestly say they kept an open mind to the handful of such paradigm shifts we’ve experienced in the last 20 years?