The surge in altcoins has led many traders to forecast the dawn of a new altcoin season. According to "The Moon" a pseudonymous Twitter analyst, altcoin seasons follow a major run-up in the price of BTC, especially when the price stalls or pulls back.
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This means that altcoins can affect the value of Bitcoin prices, if you look at the content of the posts you share, this is not wrong in the general picture, even almost everyone says this, moreover an analyst has started talking on twitter, this greatly affects people's actions in decision making.
Today if we look at the market conditions, almost all altcoin prices are rising, even bitcoin is no exception. And vice versa, if altcoins go down then bitcoin will also experience these effects, all of this shows a very close level of influence and dependence on all of them.