The source and delivery of gold, or even the entities that makes gold into financial tools can be regulated, but not Bitcoin, one exception is if the Chinese goverment really do control most of its mining power, then like gold, Bitcoin will be controlled.
One of the many things I realized in the existing systems we have in this world is that there are so many ways to control a thing and they can easily do subtle things to get the results that they wanted. Technically, it would be impossible to control Bitcoin but the price that can easily be manipulated to go up or down. Just ask China to declare an all-out war against BTC and let's see if there will be an abrupt dump all over the world or you can also ask China to officially proclaim that they are supporting BTC and you can be sure that the price can be going beyond the roof. That is the kind of control that governments and central banks have. But why are they are not doing it now? All because these people are not yet looking at BTC as a big threat.