If you look at predictions people either expect Bitcoin to be worth nothing in five years, or hundreds of thousands of dollars (or more). No one is predicting a price close to where we are today, and that makes sense given its utility, assuming it can scale and that no other contender arises to take its place.

So if you're not a skeptic it makes sense to hodl, and that means buyers are going to keep driving the price higher. Far from being unsustainable it looks very sustainable. I just wonder what happens as blackouts start spreading due to mining on a global scale.