The price of the cryptocurrency bitcoin dropped dramatically Friday, losing 25 percent of its market value within 24 hours. The infamously volatile digital currency was hit by a wave of selling just before Christmas, plummeting by $121 billion of its total market value in less than a week. The quick fall surprised many investors, according to The Wall Street Journal. โThereโs been a lot of talk about how bitcoin is in a bubble,โ said Jani Hartikainen, a software developer in Finland who owns a slew of digital currencies, including bitcoin. โIf I keep holding this, how long is it going to keep going up in value, and if it starts crashing, am I going to have enough time to get out of it?โ Hartikainen sold almost all of his position early Friday morning.