Since most of the major altcoins move up or down at the same time as bitcoin, aren't they all controlled? How does it work?

- Since they are equally volatile in the market, their values will not move the same if there is no seller or buyer, this is the usual reason why there is movement in the market.
If there is a sudden increase, this is probably because many holders are positioning themselves to prepare for the sudden kicking of its price and vice versa for the decrease in its value as well.