Most of the speculators before and even now are saying that if Bitcoin goes up, then altcoins goes up as well and good projects perform well. How true are these speculations if there are different technologies or plans for each cryptocurrency? And the fact that bitcoin is not even the first cryptocurrency.
It's a speculations, rather than that, what I've been seeing for the past years was if bitcoin price goes up, the others will follow behind them. But if bitcoin price falls down, the majority of altcoins will suffered the most more than bitcoin price decrease.
According to wikipedia bitcoin is indeed the first decentralized cryptocurrency. But we might need more research on that one.