I think this happens due to the algorithms of trading bots, which are similar to each other. Even now, three years after the opening of this branch, the similarity of the charts is very expressive both on the leading coins and on altcoins, including all of them tied to the bitcoin rate, since the main trading pairs are pairs to bitcoin and the dollar token. In addition, whales do not trade with their own hands, algorithms do it for them, and large sums combined with algorithms move the market equally in all currencies.