When bitcoin rises, the altcoins keep the price and if when the bitcoin falls the altcoins fall even more. Why do altcoins usually follow bitcoin?
Because bitcoin is an icon of cryptocurrency itself, everyone must be familiar with bitcoin before learning about other coins.
In fact, before there was a stable bitcoin coin first became the only fair to trade because bitcoin would be trusted by everyone.
making bitcoin the leading direction of all cryptocurrencies. Usually, a professional cryptocurrency trader will look at the bitcoin price before he starts investing in the altcoin of his choice.