The best time for buying is at low price and I think if you sell your coins with profit then you should not regret after Fluctuations in coin price because you have already taken your profit so ready to make another step instead of regret about past.
If you are in doubt about other coin then just buy bitcoin now and don't sell until you achieved your target. This time is not suitable for selling but if someone is in huge profit and he cannot hold longer then selling should be preferred. Understand the market and accept your profit but I think if someone is selling their bitcoin without waiting more so he will miss the opportunity of having huge profit in Bull season.
for me the time you buy doesn't really matters but when you sell, if you have a plan of selling when the value is higher then no matter what you spent during your purchase you are sure of making some profit because you already have a plan and you are committed to this plan not minding what the prevailing circumstances are, and then when it is convenient for you then you carryout your transactions, perhaps this is where the long term approach comes in.
I don't think the mentality of selling Bitcoin after the price increases has anything to do with long-term investment. Because the price of Bitcoin can increase a lot even within 1 year. This does not mean that you have to sell Bitcoin if the price increases within 1 year. This can never be a long-term investment strategy. The price of Bitcoin fluctuates a lot, but after a long time, its price becomes several times higher. That time should be 4 to 10 years or more. As a result, real profits can be made by investing in Bitcoin. Therefore, it is necessary to get out of this mentality of selling only when the price increases and follow the complementary approach that should be adopted to continue investing effectively for 4 to 10 years.
It is true that the price of Bitcoin may be higher than we fear, but if you prepare yourself now and be aware now, in this case none of us can say for sure what the price of Bitcoin will be tomorrow, so it can also be said that the price of Bitcoin in the future may be much higher than today, in which case you need to be patient and stick to the long-term path for investment, and if you really come up with a short-term plan, then this is a big wrong decision, because by doing this you may be afraid of the short-term price fluctuations of Bitcoin and you need to understand that this is the natural nature of Bitcoin, but experienced investors are familiar with it, so it will be useful for new investors to move forward with long-term goals.