$BTC so if one buys a coin with BTC...the value of BTC will determine the value of the purchase. As we all know. Now, since most coins behave exactly like BTC is it safe to assume that is because most are bought with BTC? Dunno if my theory is sound but if all coins were bought with FIAT or USDT, would they behave their own way instead of like BTC? Bar forex fluctuatuon...