Obviously #Bitcoin price is set by bids / asks and people buying/selling.

But as any natural or human-made phenomenon it can be studied using statistical and probabilistic tools.

And yeah models can be built to try to make predictions.
That's literally the basis of Science:  Observe, build a model, make predictions, refine the model.

And yes models are built using equations. Does that mean equations govern the natural phenomenon ? No, it means it describes the phenomenon up to a some precision.

By the way, many natural phenomena can be described by power laws.

You should try to learn more about power laws, you can start with the wikipedia page i guess:
#Bitcoin