Quote from: cryptoaddictchie on Today at 12:49:21 AM

Because its the main coin or the leading cryptocurrency. Almost all of these altcoins are in pair with btc or so to say that has been related to bitcoin. Its safe to say that whatever bitcoin price, all other coins will be affected to it.

Additionally to trading pairs, I think that the success of any altcoin project depends on bitcoin adoption.

As most of them share the same technology (blockchain), it is safe to say that regulations/limitations/security/etc on bitcoin will also have a direct impact over altcoins.

Nobody gets to know ethereum or ADA or binance chain before hearing about bitcoin. Bitcoin is the main reason for this whole ecosystem and all altcoins to exist.