The logic here is simple you just have to buy when it's low(red) and sell when it is high(green) but with such manipulation in almost everything is a bit agony to almost all traders but i think if you are a long-term trader it won't bother you anymore as long as you know what you are doing.
Buy low sell high isn't all that easy for the majority of the people. If we look at the peak levels, and the drop to $15,000 afterwards, people said it was a good time to buy, while it kept going down. Later $12,000 was the right moment to buy, then the $10,000 level. In some cases, especially if you don't know what the market will do, it's better to just wait till you feel comfortable to enter again. Some times people tend to force themselves to enter, and that's never a good way to invest, especially so because that will only contribute to more potential panic in case the market starts tanking. In a market as volatile as the one from Bitcoin, minimizing your risks as much as possible is the main aspect. In other words, don't invest with borrowed money (e.g. credit, leverage), don't over-invest, don't force yourself to invest, don't assume the price will keep going up, etc.