People buying BCC in case the Segwit2X fork turns into a disaster that damages both versions of BTC, at least temporarily, and BCC picks up a lot of the slack. That's my take on it anyway.
How segwit2x gonna destroy original BTC chain, segwit2x is independent fork supported by few guys but they will keep mining both chains just like many miners are mining both bitcoin and bitcoin cash right now. Segwit2x will just create another bitcoin clone named as B2X. People buying BCC just because of high speculation but we have seen several pump and dump schemes in bitcoin cash before too. Expecting some correction on next few days.
.. really does not decrease 