Bitcoin is first of its kind and backed up with innovative technology and mostly people are crazy about new things, initially that was the reason then bitcoin starts gaining appreciation and adaptability but now i think price is the only reason behind bitcoin popularity.
It is because bitcoin is really different then any other coins and it was one of the first coins that came here i think. But i don't really much about the history of bitcoin so i shouldn't talk to much about this before i talk nonsense.