The answer is simple. Bitcoin is like the king of crypto world. When the king is strong and prosperous, his kingdom is also happy. Trade flourishes, new people settle in etc. But when the king is weak and has a declining health, then the effects are visible in his kingdom too. Trades become less, people start moving out etc.
Currently Bitcoin is the focus point of crypto world and represents the trust in cryptocurrencies. It is also the gateway to crypto world and is paired against the maximum number of cryptocurrencies. So when Bitcoin's prices go down, people basically lose trust in cryptos, and start selling their altcoins too; thus bringing the price of altcoins down.
As for which altcoin can escape this cycle, then the answer is probably none.
I think this answer is very complete and very clear with all the illustrations it provides. hopefully the OP can be helped with your answer. I just want to add that bitcoin also can not develop itself without any other altcoin as an alternative
right, bitcoin as an intermediary transaction to buy altcoin, so altcoin can not escape from btc. therefore if btc decreases then altcoin also decreases. and with encouragement of altcoin btc can maintain its circulation