I think people lose their ability to hold for a long run due to the fact that they felt the greed when they saw that their investment is having a considerable gain.
It all depends on a particular individual's understanding of crypto investment because there's no need for any investor to sell all her hold when she can sell the profit and keep her initial investment (in USD) which I believe is a win-win decision if the person doesn't want to miss the next opportunity the market will present.
Based on my self also, when I entered crypto Q4 of 2020 going to 2021 I made a generous gain and felt that I need to cash it out as I felt the greed and the fear that it may fall anytime. That kind of thinking I have before brought me to realization that if you believed in something then you should trust it.
You should have sell the profit after calculate it in USD or your intial investment and keep the remaining coin for long term.