The dominance of the market currently held by bitcoin, public trust in the influence of the value of bitcoin is quite high. and also its popularity is known by many people to make them believe in bitcoin
Coin market leaders are currently bitcoin, and most people believe that bitcoin is a guaranteed coin. the problem is that even though bitcoin is down, all coins will certainly go down and bitcoin will still lead the market
I don't think all movements are always like that, it still often happens when there are certain events in a coin that can indeed influence the price of the coin, so the price can go up on its own without relying on bitcoin price movements.