The "Bitcoin only" concept will fail because it'll never be viable. It's a cool toy, but let's be real here, this was never intended to buy a pack of smokes with. And honestly, if you don't see why, you should really figure out how much you pay to use fiat currency. How much is collected on "fiat network" when you lend a friend a twenty dollar bill? Who posts that transaction publicly? And what if you notified the IRS of every time greenbacks changed hands in front of you? Do you think you'd get audited? You better bet your ass you would.

My privacy is valuable to me, and I don't owe anyone a dime when I loan someone cash. I also don't have to solve cryptographic hashes to prove what's in my wallet or that I'm not double spending.