How exactly did we arrive at this bitcoin phenomenon?

Silicon Valley’s obsession with cryptocurrencies requires no more evidence than the incredible rise of bitcoin, the alternative currency that crossed $10,000 in value on Tuesday in what is a watershed moment for the nine-year-old cash substitute.

Bitcoin has now doubled in value over the last three months — a run fueled by new interest from institutional investors like venture capital firms but also old passion from longtime enthusiasts for a once-niche payment platform. China, however, remains a looming threat.

“You’re seeing a wall of capital moving in — and if you’re looking at the fundamentals, it’s pretty stable underneath,” said Miko Matsumura, who founded a cryptocurrency exchange and has invested in several funds and startups centered around bitcoin. “You can’t have the phenomenon without both sides.”

Behind its rise is also a desire by global investors to insulate themselves against their own currencies depreciating in value. People who are nervous about money backed by a central bank with unclear controls — such as China’s — have become attracted to bitcoin, an open source currency that is less influenced by the state of the economy or any looming geopolitical risk.

But to say concerns about a bubble persist would be a massive understatement. It has crashed — hard — several times before, thanks usually to new crackdowns from China. Bitcoin’s pace of growth — plus the mere fact that as a digital currency it is not backed by a government or an army — makes more than a few analysts worry that this craze is due for another crash.

For now, though, it’s on a warpath worth some awe.

This article originally appeared on Recode.net.

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