Bitcoin is the first in cryptocurrency and it actually affect on the whole cryptoworld. If bitcoin really bubble one day, all the cryptocurrency will definitely affected as users will start to lose confidence in. Just like investment, all the crypto is actually based on the investors, or we can say user's trust and confident.
Since December, bitcoin is having a downturn. Until January they really experienced a major crisis in just 2 months time! A lot of bad news are coming out from China and South Korea government, making investors losing confident in cryptocurrency. A lot of investors will think Bitcoin is going to bubble, which means that crytocurrency is going to bubble as well!
(From: https://www.theonion.com/bitcoin-plunge-reveals-possible-vulnerabilities-in-craz-1821134169)
In my point of view, although others cryptocoin will be affected, but it will be stabilize after months, which actually might be half a year and above! If the investors are patient enough, it's better to wait than pulling the money out to fiat money.