Bitcoin, unlike traditional currency, is not controlled by any bank or government as it is a decentralized currency. Everybody has a say when it comes to bitcoin as it is an open source network and there is no supreme leader that controls it. In retrospect, it is majority vote that controls bitcoin as all nodes are equal in the bitcoin network. This means if the majority of bitcoin users decide something, the decision is final.
The bitcoin network, on the other hand, is controlled by the developers who are still looking for various ways to improve the network. In this case, the majority of developers decide which angle the future of bitcoin takes.