My worst experience is selling altcoins with potential so I can sell early because the admin wasn't active and there weren't very good updates on their project but that was a lesson to me and I didn't become a strong holder of my altcoins so I should be patient and also don't be greedy especially in investing.
I have felt the same way to sell a coin that I didn't expect to be a big coin this year, I regretted selling at that time and started to hesitate to buy when the price was high now. was forced to just be silent to contemplate that doing a foolish move.