mortality
Experience something horrible.
I grew up in a ridiculously perfect fantasyland. My parents, who have an ideal marriage, told me I was the best at everything, encouraged every dream I had, paid for college and insulated me from all of life's difficulties re: money, stress, etc.
To make matters worse, I excelled right along with the praise -- made good grades, got into a top-10 college, started a company after college which was lifestyle-profitable for 7 years. (It could have been a major score if I'd executed better, but that's beside the point.)
When my company started to decline post-2008, I had to go get a job. I excelled at it, but got crossways with my boss for entirely personal reasons and was fired.
This back-to-back double-whammy was by far the worst experience of my life. I'd never experienced failure or rejection and my psyche/ego simply didn't know how to handle it. I sunk into a depression for 3 years. It's not hyperbole to say I almost didn't survive it.
But I'm on the other side of it now. The darkness is receding. I know this because I know the double-whammy was entirely necessary for me. The spoiled brat is gone. I empathize with others. I care about the journey people have taken to the point where I meet them. None of that mattered before. It was all me, me, me, the worldbeater.
Yeah I'm in my mid 30s now and the past 5 years were tough. But I'm glad I've already spanned the chasm now than in my mid-50s. Now I'm better prepared for things to come.
One slightly separate piece: I used to have massive entrepreneurial angst. I was a person who looked at those who have "made" it and got angry. Angry at lack of co-founders. Angry that my school's alumni network doesn't have the best SV connections. Angry at perceived ageism in tech circles... But now I know that all advantages others might have on you -- better schooling, younger, lucky career breaks, etc -- can be trumped by one thing: traction. It doesn't matter if you're white, black, purple, one-armed, blind, gay or republican -- If you have something worth investing in, you can find investors. Period.