Mass human psychology, the price rise leads to more people buying, from 'fear of missing out'. Also unsophisticated investors pile in after all the news coverag

Mass human psychology, the price rise leads to more people buying, from 'fear of missing out'. Also unsophisticated investors pile in after all the news coverage of the price rises. This all creates a self reinforcing dynamic, where further price rises feed even more of this sentiment, which leads to more buying and price increases.