when bitcoin rises then altcoin prices will also rise but when bitcoin prices fall, altcoin will also decrease as altcoin does not have the courage to do very much increase while rising bitcoin prices and i think altcoin many follow bitcoin price movements because altcoin price exchange depends on the bitcoin price
One thing which is true about the Bitcoin is its action like base currency and is known as base currency of the crypto market which has affect on other crypto coins. This is due to its nature which creates same perception on the whole market as all are digital currencies so increase or decrease in the Bitcoin will have affect on other currencies too. Experts say that this affect will finish in future with the passage of time when these technologies get more success.