Likewise, people were very skeptical about centralized currency/printed money when it was first introduced. Or if you want something more recent - skeptical that industry would ever surpass agricultural production, or services would ever overtake industrial goods, without destroying economy. Doesn't mean it _can't_ happen...
If you look at what fiat money had become in past, e.g. Germany of 1920s, you'll see that the doubts were quite founded. Even if you take a look at most important modern currencies, you'll see how much trickery is involved (quantitative easing, etc).
