Bitcoin has the widest adoption, the most hashing power backing it. Bitcoin is the only cryptocurrency which people know in some countries.
So the dump bitcoin and then accumulate is not such a wild theory after all.
that is true that bitcoin is already know in many countries but they don't know more about altcoin. so if they see that bitcoin price is getting down, then they should thinking that is the right time to invest their money in bitcoin. i think there is always some people wants to make people in the market getting panic and they sell their bitcoin so the other people can buy bitcoin with cheap price.