It's already part of the industry. Like any other players in the market, they normally depend on the supply and demand which is the basic factor why the value of a certain player consistently change.
Why bitcoin rising up and down?
can any person tell.
supply and demand...basic concept of economics
low supply and high demand = high price
high supply and low demand = low price
To sum up, the whole concept of the law of supply and demand. Also, there are outside factors that affect the value of Bitcoin, such as; News (Fake or Real), Public announcement, Government bans, and etc. That causes or contributes to the volatility of Bitcoin.