I doubt that it us only beginners that does this, from what I understand, it is the mindset that they used to venture into bitcoin investment that will control your emotion and thoughts. There are still some people that are old in bitcoin that are also carrying out such practice, because they never have any plan to invest for a long period of time and also to have a bitcoin target and how to achieve it.

However, sometimes it works for them and they feel that they are smart but not knowing that they were only lucky to sell at the right time and the price of bitcoin dips to favor them, but most times they make wrong decisions and sell thinking that the price will dip but only for the price to keep pumping and they will regret their actions because they will not be able to buy back till they miss out.

This is why a newbie should have a long-term goal mindset with a bitcoin target, so that s/he can stay focus on accumulating with regular DCA at any time either in the bull or dips to grow his/her bitcoin portfolio. With this, you will never think of selling until you have reached your bitcoin target or very close to your bitcoin target, as long as he has made available emergency funds and reserve funds down.