Each day, more and more people start investing in cryptocurrencies like Bitcoin (CRYPTO: BTC). It's not hard to understand why. Over the past decade, the S&P 500 has risen roughly 278% in value. Bitcoin's value, meanwhile, has soared by more than 17,000% over the same time period.

If you want to add huge growth potential to your portfolio by betting on crypto, there's only one ETF that most investors need.

There's a reason why Bitcoin is so famous

When talking about Bitcoin six years ago, legendary investor Peter Thiel summarized the investment pitch for the cryptocurrency: "Money is the bubble that never pops." Consider the U.S. dollar. It holds value because everyone believes that it holds value. There are some backstop forms of value such as military might and the power of taxation. But in general, currencies like the U.S. dollar -- or even stores of value like gold -- have value because we all agree that they have value.

When it comes to investing, the rule is typically to find opportunities that will create hard value in the form of distributable cash flows or real world profits. Betting on what other people think the stock will be worth can be a dicey game. That's why most experts build complex models and analyze financials to determine whether the price they are paying for an investment will be worth the eventual reward.

Currency -- or more colloquially, "money" -- is the exception to this rule. Dollar bills don't produce more dollar bills. That's not where their value stems from. Their value, on a core level, is as a social instrument. We all agree that it represents the value of whatever work was put into earning it. Bitcoin operates in very much the same way. It's considered a proof-of-work cryptocurrency, meaning miners are continually working -- in this case, they're solving complex mathematical problems -- to produce more Bitcoins. And while it doesn't have much direct functionality besides as a form of money, it's the first time a form of money has been created that doesn't involve major nation states or other centralized powers.

Of course, a bunch of other things are happening in the crypto universe as well. And it's possible that crypto in general enters our daily life in ways we never expected, just as the internet continues to do. But regardless of whether those ventures are successful, Bitcoin will always "work." That is, it will always retain its ability to act as a form of money and a store of value.

This is the only crypto ETF you need

Due to these factors, most everyday investors only need one ETF to gain exposure to cryptocurrencies: the iShares Bitcoin Trust ETF (NASDAQ: IBIT).