Why do people sell their Bitcoin due to fear of the current drop in price. Do They feel the price will drop further and never go up again ?
There are several reasons why they do that, some think that it has entered a bearish market phase, they can't afford to wait and see the portfolio continue to turn red plus maybe they have needs in real life.
Others think they can minimize losses by selling early, it could be their analysis that prices will fall further, so they can buy at a cheaper price and can maximize profits with a predetermined target.
I feel before anyone invests on Bitcoin they should get a proper understanding of how the Bitcoin market operates. Because if an individual has good understanding they will know that the rise and fall in price of Bitcoin is normal so there won't be a need to panic rather see it as an opportunity to accumulate as much as possible in anticipation for a rise in price.
What you said is true, however, everyone has different strategies in finding profits in the market, DCA is not always the best strategy used by all holders, this strategy is only useful for long-term investments.