Why does the entire Crypto market slump because Bitcoin does? Over asked question, I know, but hear me out.

It seems that most coins have entirely different purposes and exist is totally separate ecosystems. If that’s the case, then does the rest of the market fallow Bitcoin because most coin holders aren’t wise enough to know the separate nature and act out of ignorance when panic selling? Is it also possible that some of these investment groups are starting to put big money into more and more alt coins and are having a wider effect on the market? I’ve heard some explanations as to why bitcoin runs the roost. Things like, “it’s the first/pioneer coin” therefore, it’s the canary in the coal mine. “It’s the most secure” therefore, if it’s value tanks then that must mean that other coins can’t thrive. Are there any other prevailing theories? Thanks for your response.