While I don't agree everything Warren Buffet is doing, mostly because I think there is more to it than simple one liners: but this one resonates really well with my view of the world:
When Warren lectures at business schools, he says, “I could improve your ultimate financial welfare by giving you a ticket with only 20 slots in it so that you had 20 punches—representing all the investments that you got to make in a lifetime. And once you’d punched through the card, you couldn’t make any more investments at all.”
He says, “Under those rules, you’d really think carefully about what you did and you’d be forced to load up on what you’d really thought about. So you’d do so much better.”
To your point about diversify, some people are so diversified that they don't even know what are qualifying economics what price to get in or get out. With that I think that thinking 10 times about something before getting is super important, and not FOMOing any coin is critical in making good decisions and living a healthy life.