I'd guess by don't reach to the fluctuations means don't panic? As traders, we must always naturally react to changes in the market since our plans that we have set may be changed depending on the market fluctuation. Besides, Reacting is not solely limited to panic buying or selling after all, so OP's topic may seem a bit confusing.
Although I get the idea, those that panic in face of fluctuations are either short term investors or those that are newbies to trading. Most people who have experienced HODLing over the 2017 bubble should be already quite experienced with such fluctuations and should be able to react positively to such events.
We have been doing same mistakes again and again ...
If you did it few times you should learn. Everyone need to do few trades to understand that he is a small fish and that Whales will eat him. You learn best by doing it. OK some people are smart enough and know how to listen. For the rest of us we need to learn on our mistakes. But if you repeat same mistake again and again, then I dont really know what to advise you beside to visit your doctor and ask him to get you a specialist.
Indeed, get a specialist. You need help. Like immediately. It's like you lost the basic inheritance of a human being who learns from his/her own mistakes.