There different words for cheaters; scammer can be considered as cheater, thus, cheaters are one of the reasons why cryptocurrencies are going down. Their greedy attitude caused every coins to fall. If only, they are fair, maybe bitcoin is still in the high peak.
How are cheaters causing the price to fall? I don't see any connections. Cryptocurrency price are based on supply and demand if you forget. Greedy is another thing, and always when you are greedy in this game, you are going to lose in the long run. And you can't blame people from selling their bitcoin because this is a free market. If you don't want to be a victim here, then be smart.