Bitcoin: fad or the future? The question has dogged the digital currency since its inception nearly a decade ago, and recent developments raise it anew. Last week, a new variant of bitcoin emerged via a "fork" in its underlying code, threatening to confuse and divide the still-small world of bitcoin adherents. Meanwhile, the price of a coin has soared to record heights above $3,000, from about $1,000 at the year's beginning.

Skeptics remain. Consider the severe missive penned in late July by Howard Marks, who runs Oaktree Capital, which manages north of $90 billion. Marks wrote to his investors that "digital currencies are nothing but an unfounded fad (or perhaps even a pyramid scheme), based on a willingness to ascribe value to something that has little or none beyond what people will pay for it." Not surprisingly, he cautioned clients about investing in the currency. His perspective is widely shared, amid concerns about the currency's recent price spike and extreme volatility. Past security breaches on bitcoin exchanges, as well as the limited options for using bitcoin in transactions, only add to the skepticism. The "bitcoin fork" will do little to allay such anxieties about an unfamiliar form of currency that relies on software and a network of computers linked over the internet to record and process transactions.

There's nothing particularly new about Marks' critique. It reflects suspicion of the unfamiliar. On one level, it's hard to see what the fuss is about: Even after its recent surge, bitcoin has a total market valuation of about $55 billion. The next-largest digital currency, Ethereum, has also spiked in value, yet still amounts to less than $20 billion. That compares with a global asset market of stocks and bonds and loans of nearly $300 trillion. Bitcoin gets a good bit of hype but remains tiny.

Instead, the attention seems derived from what these currencies might become. Bitcoin's promise – that it can supplement and ultimately supplant national currencies and global financial institutions and allow for seamless commercial transactions without either banks or governments – is vintage Silicon Valley: disruptive technology opening new avenues of exchange and enrichment, empowering individuals, and weakening the hold of the state and large corporations. For now, of course, promise is about all it is, and that's why it attracts such skepticism.