Probably the worst characteristic of gold is that it can be easily confiscated by the government if another ban on ownership of gold were to be put in place, unlike bitcoin that can be very difficult to confiscate if you take the right measures.
Gold as an investment is most popular in the US, but there the possession of gold is said to be well correlated with the possession of guns, so come and take it. Apart from that, nowadays metallic gold can only inspire interest among gold bugs and central banks. Consequently, the government (by which we obviously mean the US government) doesn't need either to ban gold or confiscate it. Given the amount of paper gold out there, they could just directly affect the price of it, and no one apart from die-hard gold addicts will be interested in it any more. Hard assets are very vulnerable in this respect...
Just create a derivative market for them, and they are basically done with (whenever you need that, of course)