The problem u r talking about applies to coin shops/traders like CoinBase who directly buy/sell coin with their own fund. U'll see they always buy low and sell high and they never hold unless they really predict the market to go up for some certain reason.
Yes that's what I mean. What if those traders have all these people who just made a huge profit and trying to sell back to them for fiat before the rate drops, and no one is buying coin, but everyone is selling it, then how can the trader afford to pay so many people at such a high rate in that situation?