If you saw price chart you seen that when bitcoin price increase many alt coin price dump. When btc price fall down you see alt coin price don't increase.
Well, it's not all altcoins could be affected from Bitcoin. But, the majority of it is get affected by Bitcoin's price movement.
I think 2017 and 2020 has some similar stuff, but the biggest difference is we started from 700 dollars and reached to 20k in 2017 and that was too unrealistic and unsustainable, here in 2020 we didn't had something like that, from around 9k to 27k levels is not that weird, it is just 3x and totally sustainable as well.
But still the mainstream media makes it too hype and attract more potential investors into cryptocurrency, even though they are just following the hype train and once the hype is gone they will go back to shittalk cryptocurrency again like in 2017 lol