you are only 50% correct, the second part is right.
holding something that you believe will appreciate over time (in long term) doesn't make you an idiot. and many are doing this because they do not trust exchanges to start trading bitcoin there and other means of selling are not good enough.
holding something that is useless and has an illusion instead of future (ie altcoins) makes you an idiot though.
I agree, first not all people who invest on bitcoins/market does not have time to check the prices or trade everyday. As an example warren buffet is holder he hold stocks for long term, he is just a billionaire do you think his strategy is stupid.
If you know that you bought has great potential price correction will not matter because in the long run their value will go up.
To be fair, the holders have already profited, especially for the early adopters, therefore they are not total idiots. In fact, they were geniuses to hold bitcoin because some of them may be already millionares today. We can’t say that does who will hold altcoins are idiots as well because there are those which have the potential to be of high vaue in the future. Not all holders are idiots, but not all holders may profit as well. I think panic sellers are the ones who should be called idiots, or perhaps a lighter term would be inexperienced beginners.