Some investors are generally interested in buying more BTC at DIP prices and tend to sell during bullish times. But holding is more important because it will happen again and again when ATH is observed in the market with gap of few months.
You are wrong about this and my advice is that you should let investors do as they wish, after all, both classes of investors are aiming to earn money through Bitcoin and indeed they will earn it if they speculate and actualise it well. The exception is that one investment style will earn more than the other. Also, contrary to your view, it is those who invest when the trend is bullish and divest when the trend is bearish that will earn more money from Bitcoin, not the HOLDers if the high price of Bitcoin is to be observed.
In my experience, HODLing is a context that is being exaggerated, but of course, it worked well in the past, which might be what has entered into the heads of many, but the positive effectiveness can't be the same when the price of Bitcoin is already high. For instance, those who bought Bitcoin at $32 and continue to HODL it will have fortunes in their account now. But those who tried such when Bitcoin is at about $65,000 will only be deceiving themselves because they would be neglecting many facts/factors by doing that.
They should know that at $65,000, Bitcoin is already heavy, and the popularity and liquidity of the coin when it was at $32 can't be compared to when it is at $65,000 are not the same. More investors and better adoptions were still possible when it was at $32, but I wonder who will push it significantly upward to gain more than 200 times when bought at $32 in comparison to when bought at $65,000?