By Coinmarketcap ATH was at $20,089 at December 17 2017, and 2 weeks later price is drop at lowest $12,755. It just show that it was a pump based only on speculation, on which some smart people make big profits. I would not say that 2019 is in any way similar to 2017, and that we should not expect to see anything like 900% or similar increase this year.

Bitcoin is unpredictable, but I would be very surprised to see anything more then $20 000 at the end of this year - except in the case of some big positive thing, but something like that at the moment is not in sight.