The worst for me would be is postponing for trading. It's only good if you only bought and hold btc but I highly doubt it for most of the traders. So postponing is like being an irresponsible trading because things can happen fast in crypto and just taking an off for months can give you a lot of surprising changes that will definitely tell to yourself that you messed up. Panic selling will only happen on you first trades because you will learn valuable things as you move forward.
I think every process always has a certain amount of bad points and but it also has certain luck in that badness, we can hardly say what will bring us worse because as you said, delaying trading can be irresponsible but sometimes you forget it, you will not need to sell too soon, it will even return very well after a while we forget. A panic sale may say we are inexperienced but sometimes it will lessen worse situations, which is also quite a lucky thing, in general, we should avoid these situations