Initially there use to be panic attack in the whole crypto community and this always made things worse. Bitcoin used to be dumped like crazy and mostly it was used to be invested into altcoins for through the fork period. Now the thing has grown very wild and people now know that they get the free coins along with the fork if they keep the bitcoin into wallets or over the exchanger and thus they can make money out of it by doing nothing.
Soon people realised this and whenever the forks started happening people went out crazy and started buying as much coins as they could whenever here was fork. So now you see yourself what is the effect of it, bitcoin gets pumped very hard but it is natural pump as people are not doing it intentionally but they are doing it for the benefit of their own trade.