People probably noticed that bitcoin is hard to move, as well as xrp and eth, all coins in the top 50 are probably very difficult to move because they all have high volumes. Nonetheless, they realised they could make some money if they get together and make moves on the small ones like the pump and dump scheme, they don't care about the coin itself, they don't care what happens to the families they leave behind, all they care about is their money.
The volumes that you see in most exchanges are not real, there have been several instances in which exchanges have been found exaggerating their volumes to try to attract more clients as that makes their exchange to seem more attractive over the competition and there are also many coins in the top 10 that despite their size can be easily manipulated and some easy examples are the bitcoin forks which are controlled by a minority of people that can move the price a they wish.