Its simply due to the people emotions are driven by the bitcoin price movements, we all knows that bitcoin is the first and best cryptocurrency ever made so crypto community has high hope on it so all their decisions based on its movements which is why the price movements of other cryptos are proportional to the bitcoin.
Why though? Have you ever considered why bitcoin price movements impact people's emotions so much? I mean I feel like we should not be really getting too much attention like this whenever price moves one way or another, it should be a little less impactful for us. I still have no clue why we are doing any of this, like let's say when the price went to 28k levels I was not worried, and when it reached 40k I was not happy, I was calm.
Like the zen master and the village people story, one day a boy gets a horse as a gift and village people says how wonderful, zen masters says we'll see, then boy falls from horse and breaks his leg, everyone says how awful, zen master says we'll see, then a war broke out and all the boys are sent to war but boy stays because his leg is broken, village people say how wonderful, you know what zen master says? We'll see. That is how we should act with prices of cryptocurrencies.