Update: I won't be investing in bitcoins after all, as Vox editor Ezra Klein explains. I apologize to readers for the misstep.

I've long been a Bitcoin optimist. You can read my case for Bitcoin here. But a few weeks ago, I decided to put my money where my mouth is and invest in Bitcoins.

This isn't the first time I've invested in the cryptocurency. In early 2012, I bought some bitcoins for around $7 each. I held them until May 2013, when I took a new job at the Washington Post. The Post's strict ethics rules required me to sell them for around $120 each. That proved to be a huge missed opportunity, as bitcoins skyrocketed to more than $1000 before the end of 2013.

After I moved to Vox in March, I was allowed to own Bitcoins again. (I'll be disclosing my holdings as appropriate and staying away from day-trading.) The value of Bitcoins has fallen significantly since last year's highs: you can now buy one bitcoin for around $500.

Obviously, the price is unlikely to go to go up by a factor of 100 like it did over the last three years. But I'm optimistic my Bitcoin investment will pay off. Here's why.

The case for Bitcoin

Bitcoin is both a currency and a payment network, and this fact has caused a lot of confusion. Some of Bitcoin's most enthusiastic advocates focus on Bitcoin's potential as a new currency; they see it as a direct challenge to the dollar and the inflationary ways of the Federal Reserve. This doesn't make very much sense; after all, bitcoins have in some instances lost more value in 24 hours than the dollar has lost over the last decade.

But Bitcoin shows promise as the world's first completely open payment network. Conventional financial networks such as Paypal and Mastercard are each owned by a specific company, which sets the rules and charges people for access. In contrast, no one owns the Bitcoin network, and as a consequence there are few limits on what you can do with it.

Open technology platforms are often fertile soil for technological innovation. A quarter century ago, many people dismissed the internet as an impractical toy for computer nerds. They saw centralized online services such as AOL and Compuserve as superior. And in many ways they were. But the internet's critics didn't understand the power of a computer network where anyone was free to innovate. People invented things like the World Wide Web, Google, YouTube, and Facebook, vastly increasing the internet's appeal.

Bitcoin optimists — and I'm one of them — think something similar will happen in the electronic payment market. They predict that a faster pace of innovation in the Bitcoin ecosystem will eventually allow Bitcoin-based payment services to outcompete conventional payment technologies.

Some Bitcoin applications

What, specifically, could a Bitcoin-based payment service do better than conventional payment networks?

International money transfers seem like one example of low-hanging fruit. Conventional money-transfer services like Moneygram and Western Union charge high fees while offering rather slow service. These companies are highly profitable and highly resistant to change because it's extremely expensive to maintain a network of storefronts around the world.

Bitcoin could dramatically reduce the barrier to entry for competing with conventional money transfer services. Entrepreneurs in different countries could help customers convert between their local currency and Bitcoin, and then use the Bitcoin network to actually send the money. Small firms in India, China, or Brazil would be able to send money anywhere in the world — without worrying about how the recipient would convert bitcoins back to the local currency. Low barriers to entry could mean more competition, lower prices, and higher quality service.

A more ambitious use for Bitcoin would be to compete with conventional credit card networks. Already, a growing number of merchants have begun accepting Bitcoin payments. However, a lot more work will be needed to build user-friendly services that allow consumers to make Bitcoin payments. But once again, the low barriers to entry for Bitcoin-based services — more Bitcoin startups are being created every day — means that lots of people will be trying to figure out how to make Bitcoin payments more accessible to consumers.

Most exciting is the possibility that Bitcoin could be used to create new types of financial services that don't exist now. It's hard to predict what those might be, but open platforms have a way of surprising us.

How much are bitcoins worth?

Right now, all of these potential mainstream applications are in the future. Much of Bitcoin's current value is attributable to speculators (like me) betting that it will become more valuable in the future. So why do I think bitcoins might still be under-valued?

In the long run, the value of any currency is related to the volume of transactions conducted using it. The more Bitcoin transactions occur, the more valuable the currency will become. Right now, the value of all Bitcoins in circulation is around $6 billion. Right now, many bitcoins are held by speculators, but if it became used routinely then we might expect each bitcoin to be spent about once per month, which is a typical rate for conventional currencies. Based on the value and number of bitcoins today, that would correspond to $72 billion in Bitcoin transactions per year.

That would be about as large as the Western Union network, which transmitted $79 billion in 2012. It would be a third the volume of the Paypal network, which transmitted $7000 per second in the second quarter of 2014 — or around $220 billion per year. It's 50 times smaller than MasterCard, which processed $3.6 trillion in payments in 2012.

These are only ballpark estimates. The average amount of time people hold volatile bitcoins might be significantly shorter than the average time people hold much more stable dollars. Higher turnover would mean lower bitcoin values.

Still, the value the market puts on bitcoin is pretty modest. The market thinks bitcoins will be roughly as widely-used as Western Union or perhaps Paypal.

If my prediction about bitcoin becoming the foundation for a new generation of financial services comes true, it has the potential to be much bigger than these conventional financial networks. It's also quite possible — perhaps even likely — that Bitcoin will fail to get significant traction in the marketplace. In that case, Bitcoin's price could fall significantly from its current level of around $500.

Should everyone invest in Bitcoin?

The standard investment advice, which I myself have given, is that ordinary investors should invest in broad, diversified mutual funds rather than trying to pick hot stocks. Putting a lot of money into Bitcoin runs counter to that advice.

So why am I doing it? First and foremost, investing can be a form of entertainment — it's fun to try to predict what will happen to the market, even if statistically speaking your odds of beating the market aren't any better than flipping a coin. My Bitcoin investment is small enough — less than 5 percent of my total retirement savings — that it won't be the end of the world if Bitcoin's value plummets.

But there are two specific reasons I think I've got a decent chance of making a profit. First, the Bitcoin market is a lot less liquid than most assets. Most investment assets can be purchased from a variety of sophisticated, and heavily regulated, banks or mutual fund companies.

In contrast, if you want to buy Bitcoins you have two choices: you can entrust them to a Bitcoin startup or you can store them yourself. Both of these options involve risks — hackers, hard drive failure, financial fraud — that aren't present for conventional investments. But that may also leave room for appreciation as Bitcoin mutual funds become available to the general public.

Secondly, I suspect large scale investors (who do have the ability to put their cash into Bitcoin if they want to) systematically underestimate the potential upside of a platform like Bitcoin. A few weeks ago, Marc Andreessen, the creator of the first commercially-successful web browser, told me about the pervasive skepticism he faced in 1994 about the internet's future. Perhaps large investors are making the same mistake today.

Still, it's important to emphasize that investing in Bitcoin is insanely risky. In addition to the obvious risk that the value of bitcoins will plummet, there's the additional risk that hackers, hard drive crashes, or other misfortunes will destroy your Bitcoin holdings. There are no regulations or deposit insurance protecting Bitcoin investors. So unless you're sure you know what you're doing, you should probably keep your cash in safe assets.