You linked to a message of yours from 2015-08-15, but there was no big drop on that date. There was just another small drop like there had been almost every day since the $296 peak on 2015-07-28.
The big drop was on 2015-08-18, and -- again -- it only brought the price to ~$230, where it was before the "Greek crisis" bubble. The most obvious and convincing explanation is that, with the resolution of the Greek crisis, people finally realized that the Greek would NOT be buying billions of bitcoins.
Of course the Blockstream bootlickers blamed that drop on the XT schism. Since the schism had been developing for months, that was easy -- pick any random event in that story, and blame the drop on
that event.
By the way, all this fuss abut the blocksize limit was ENTIRELY the fault of Blockstream and their idiotic plans for the "fee market". If they had any sense, they would have implemented the raise in 2014 to be activated in 2016, with a two-line patch, as Satoshi proposed; and reminded everybody, a month before the activation, that very old versions of the software would stop working, so people had better upgrade or add the same patch to their software. Then the hard fork would be a non-event and NOTHING bad would happen from it.
