Its price was kept very low for the longest time so some very powerful organizations such as Bakkt (backed by the same people behind NYSE) could accumulate most of its market supply. At the moment the price is being artificially pumped up to build momentum until enough people from the public buy into it, then its price will once again start dropping faster than gravity.
You often can attribute the exact reasons why a stock price went up, but for BTC it seems to be a complete mystery black box that even the most well-versed traders couldn't tell you the exact reasons why it went up.
For stock price for example, you just knew in advanced even from last year that Beyond Meat's stock was going to be a hit. "What The Health", an anti meat industry and pro vegans documentary film, was a HUGE success last year and you could see from miles away everything was set up for this trend to become mainstream in 2019 as public sentiments were beginning to swing very positively towards it. For BTC however, everything just seems like a wild guess as no one could pin point exactly what drives its price.