it's funny that some persons will wait for moments when they see bitcoin price going up before the thought to invest in bitcoin comes to there mind and like you rightly pointed out, bitcoin price can go up and then up, up and then down, down and then down and so on. so you can't just predict that because it is going up now , this is absolutely the time to invest into bitcoin and when you see the price going down you retreat from your plan on making the investment. It means that if you even successfully make the investment, you can't hodl your bitcoin because in the event of any fluctuation in price, you will let go of your investment.
Real investors sees the prospect of bitcoin and invest a certain amount and leave it for quality amount of time while he monitor the price without getting seriously moved by any fluctuations in price that comes along the way.
It's quite funny how some people apply their strategy in accumulating Bitcoin, in the first place why would I prefer to buy Bitcoin when the price is making its way to the top instead of purchasing when the price was much lower. When the price is lower I can make a bountiful profit than when the price is in the bull run, meanwhile there is very strong assurance that Bitcoin must surely make its way to the top.
It is right time we acquire some certain knowledge and apply them, everything goes with planning and strategies, we don't just wake up and decide to make investment without studying what is involved in it.
It should be in our utmost plan that when the price is at the DIP or anything less than the last ATH it is a very good time to buy more even if a person is on DCA it still doesn't matter