I have seen Bitcoin go down in the last few days. And it also affects the price of other coins. As a beginner, I would like to ask the seniors in this forum. Why does Bitcoin greatly affect the ups and downs in the price of other coins?
Because Bitcoin is the leader and the standard of other coins. Before the blossom of stable coins, the main trading pairs on exchanges are altcoin/ Bitcoin.
Even nowadays, you have many trading pairs: altcoin/ Bitcoin, altcoin/ stablecoin, altcoin/ altcoin, Bitcoin still has its dominating effects. Obviously, with the growth of Ethereum ecosystem and other chains' ecosystems, the effects of Bitcoin are decreasing but still big enough.
People will look at Bitcoin to predict what will happen with altcoins. It is like the word look at what happens in the USA. to predict the later events (politics, economics, social, etc.) on global scale.