Because the price of bitcoin is not only speculative, but also objective, it increases as investors increase. To Price retreated to the previous level, it is necessary that there was an event that will significantly reduce the number of users, ie, will get rid of bitcoin. While such events on the horizon can not be seen, the upcoming hardcore does not attract such an event.
Significant drawdowns are possible and will be, but not global level.
Yes it is, anything is possible in life and with Bitcoin but when you are talking with rollback now maybe it will happen and maybe it will not. We witnessed the rollback last month about the issues with China regulating some things in cryptocurrency world and that Jamie Dimon the CEO of JP Morgan that spread FUD's about Bitcoin and the price of it almost reach from almost $5,000 to $2,900 low.
I think if Bitcoin will not fork this coming Segwitx2 then I can say that it is positive for an another massive increase in price because we see the changes when the August 1 event happened, the Bitcoin price pumps from $2,600 to $4,000.