More than anything what investors need is to have tough skin, as it is impossible for things to always go our way, and as such an investor will eventually make a mistake and if they are not able to endure it then they will sell for a bad price and lose money, this is exactly what happened to the people that invested near the ATH on 2021 and 2017, and the majority of them were simply unable to keep holding their coins due to their frail mentality.
A good trader will not buy all at once , the trader just has to wait if he buy at peak and there is no other option. The best strategy for a trader is to invest only 25-30% initially and this is enough for him to make profit, If Bitcoin history repeated like 2017 and 2021 then without panic our extra fund is enough for trading and this time a best trader will use 40% , Using this strategy trader would not panic as he has extra fund and now he will buy coin at very cheap price. Proper planning is also part of good trading and trader will not feel any fear even coin price dump down hard .