It's not surprising that we always see altcoin prices following Bitcoin as well as stocks following BTC prices. Even though we know that each altcoin has its own fundamentals. Many Altcoins also have technology that may be much better than Bitcoin and even have their own chains and have smart contract technology.

In my opinion, why Bitcoin affects market prices is because it's all just because of "trust", all crypto traders must have the same mindset if Bitcoin is always their benchmark. So if Bitcoin experiences a dump, they all also believe that other coins or tokens will also experience a decline and vice versa.