Bitcoin doesn't need altcoins because it was making its way by its own.Altcoins are dependent on Bitcoin which has been seen over and over again on every rise in price of Bitcoin.Bitcoin will always rule the digital/crytpocurrencies no matter how advanced they will be in tech but still will remain under Bitcoin
i also think so that the other alt coins have no such a bad effect on bitcoin, and bitcoin ca purview without alt coin, as bitcoin is still the number one crypto currency and there is no need of aly alt coin to give support to bitcoin.