Since launching in 2009, Bitcoin (CRYPTO: BTC) has rapidly become one of the best-performing investments of all time. Even small initial investments have turned into millions of dollars. But what if you had purchased just $20 worth of Bitcoin 15 years ago? Would that have been enough to make you a millionaire today? The answer might surprise you.

Roughly 15 years ago, Bitcoin first began trading hands, mostly through manual transactions conducted using online forums. Back then, a single Bitcoin was valued at just $0.00099! Online exchanges weren't launched until 2010, when its lowest price was recorded at $0.04865 on July 14, 2010.

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If you had purchased $20 in Bitcoins from an online forum in 2009, you might have been able to buy over 20,000 Bitcoins. Since a single Bitcoin is worth around $70,000 today, your $20 purchase would have turned into an astounding $1.4 billion!

But let's say you waited one more year, until Bitcoins were traded on exchanges, making it easier for you to acquire your stake. Purchasing $20 in Bitcoins at roughly $0.05 per coin would have resulted in a stake of around 400 Bitcoins. In this case, your $20 purchase would now be worth around $28 million -- still an incredible return, but far short of making you a billionaire.

Even though these incredible returns are likely a fixture of the past, there are still plenty of reasons to invest in Bitcoin today. Bitcoin's market cap of $1.5 trillion still pales in comparison to gold's market cap of nearly $19 trillion. Plus, huge sums of money are being poured into the cryptocurrency space to build out new infrastructure, networks, and services -- similar to the early days of the internet.

Where Bitcoin's price will end up over the long term remains anyone's guess. But there's no doubt the original cryptocurrency has been incredibly profitable for long-term investors with very patient mindsets.

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