Miners decide what they mine. Their contribution is what makes the currency work. They are some of the main profiteers from the currency. You can't do a fork

Miners decide what they mine. Their contribution is what makes the currency work. They are some of the main profiteers from the currency. You can't do a fork or rule change without enough miners going along (I mean you can but it would not have much value). So in practice have all the governing/decision making power (as a group not a single person). Sure they might not come up with changes, but they do decide weather any change do take effect in the end.