Bitcoin is not anonymous in and of itself. If you deposit money into Coinbase using your checking account, it deposits the BTC in your Coinbase wallet, and then you send the BTC from there to a darknet market wallet, then that transaction is fairly easily traced back to you, because there is a direct link between the marketplace and your Coinbase wallet which is tied to your dox. But, what if I were to use a VPN/Tor to install an wallet that could be used as an intermediate wallet between Coinbase and the market? It would be much harder to prove who owns that wallet (you don't have to provide any proof of identify to install a new wallet), and who exactly sent the money to the market. Basically, it's the wallets, Tor, and VPN that are anonymous, and as a decentralized digital currency, BTC can exist in that medium.
I'm kinda sick that I didn't bite the bullet and drop some coin on Ripple a couple of days ago. I was *this close* to buying some when it was $1.07, but decided against it. It reached over $1.90 today.