The price of bitcoin in September 2017 was not up-to 50% of what's it in September 2018. And by December 2017 the price increase tremendously which everybody was hoping  the price will stable in this year 2018 but some big guns keep crashing the price. Nevertheless,  the history might still repeat itself though not too certain to reach ATH of $20,000 but we could have an adjustment in the market price before the year 2018 runs out.