This is the exact confusion I have with regard to how to deal with Steemit taxes. I know we must pay something but don't know the best way to calculate it. So why is Steem different if it's not directly traded for fiat? As you said, you can buy Facebook likes or really any account with fiat or Bitcoin, but you cannot directly cash out your Steem dollars into the USD and your Steem Power cannot be purchased with fiat.