Why would you think like that ? BTC have a dozen of fork none of them make any different with bitcoin price. even ethereum have fork, do etherzero make ethereum price increase ? Spoiler alert, its not.
Typically the trend is if there is hardfork which is going to happen, for example in case of ETC fork, the mere news itself brought a uptrend in ETC graph and hit $40 from $30, although it lost its gain subsequently when entire crypto market was red in next few days. As ppl expect to gain more forked coins by buying original currency. This is my understanding.
I want to know what experts in the community think who may have benefitted from other forks !