This question already has an answer here:
Is there a physical mechanism that determines and maintains the price of cryptocurrencies, be it a robot or a human? Let's say there is a price surge and the first buyer bought a crypto unit at $1. What would make the price click up to, let's say, $2? If there isn't some kind of a software mechanism that reacts to the purchase and increments up, everyone following the first buyer would just buy at $1, right? And why do different exchanges have slightly different prices at any given time?
And I am not talking about rates. A mechanism other than demand must change the price. Otherwise how can the range be so wild with relatively low activity? There must be an algorithm that responds to buys and sells.