In my opinion, people that against bitcoin, and share fud about bitcoin, are the people that invest on bitcoin too. This is only a scheme to scare people and make people panic sell. As people sell, they will gain more profit. Usually they play this role in a group.
Here is the ilustration of it.
A person called 'a' and his group have many bitcoin, when price is high enough, they sell their bitcoin (lets say at 15k), then they start their plan, if people are selling enough, there will be a decline of price in the market (price of bitcoin will be decreasing), and when it reach the target (lets say maybe at 5k) they will buy bitcoin, and they will get more coins. If they orginally have 1, with this scheme they can gain 3 bitcoin after it is done. And who doesnt want to get more bitcoin.
People really will do anything to get more of bitcoin.