We have to accept that the fate of the altcoin still depends strongly on bitcoin, as bitcoin accounts for more than half of the total market cap and bitcoin remains the crypto king:
+ When BTC increases: the excitement of investors increases, more capital is poured into BTC, partly coming from the capitalization of altcoins, which causes the price of Altcoin to decrease;
+When BTC falls: confidence in the market falls, investors sell altcoins to protect profits.
There is only 1 case where altcoins benefit, which is that BTC maintains a good price in the long run. Then, investors will look for new opportunities in altcoins.