If you have some asset that's doing really well, and you're asking yourself "sell or not?" that is the wrong question.
A while back I made a high-conviction play on something I thought was super underpriced and would do really well. And I was right. I more than 100x'd on what was, for me, a pretty substantial investment. Anna begged me to sell. I was like you're crazy it's going to 10x from here at least. Well, it didn't. It's now worth roughly what I paid for it.
The right question was, and always is, how much to sell. The answer might be zero, but that is the right question to ask yourself. I could have sold half, and paid off the house and bought another house and a lambo, and if it really was going to 10x from there I still would have done really well on top of all that.
I'm mostly pretty good about not letting these things eat me up, but I figure I have to let it bother me at least enough to learn from it or what was the point, and maybe you can learn from it too.