now the price have to decreased from (40k- 30k) buyers pause not to purchase again, because of fear, having the mindset that the price will decrease again to (20k) before they could purchase.
So if mistakenly the price really dropped to (20k) and accelerate again to a point that is higher than (40k) which is the initial point, to (50k) the profit status of some one who purchased 30k and 20k is not same.
Using this illustration to expatiate more, those investors that purchase Bitcoin in 2010 and 2011 and bank their btc till 2019 before they sell, and those who purchased in 2019 and same 2019 profit are not same...