No one is dumping their USD into effing bitcoins. They would use gold. Bitcoins are essentially worthless as a currency right now and the entire "economy" could collapse tomorrow for any number of reasons. I know everyone on this board thinks that bitcoins are going to be the new universal currency and that every business will accept them and they will be worth thousands of dollars each, etc, etc, etc, but you have to realize that everyone on this board that says things like that is insane.
Gold is kind of worthless as a currency too. Don't know many people who would accept it for goods, and even if they did, how would I get it to them? Mail it?
Investing in gold assumes someone will be willing to buy it off of you for a fair price with currency you can use. At the moment, bitcoins are the same. But in the future, it might be possible to trade bitcoins directly for a variety of goods. It is easy and convenient. I don't think it will ever be that way for gold.
And PS, I'm dumping a good bit of my USD into bitcoin. So somebody is.