Bitcoin is main trading pairs in almost all exchanges and is major dominated crypto in the market. That is why whenever the price of bitcoin shows some fluctuations all other altcoins too shows some fluctuations. Bitcoin dominates market by 40% to 45% of market capitalization so it's obvious whenever the price of BTC goes up the total value of market capital will increase.
The crypto market is dominated by Bitcoin price movement, it may rise up the other crypto coins, but is not applicable to all coins, some are even drops its price when Bitcoin appreciates its price posted on the market. We have to remember that not all investors are Investing in other coins in the market.