Bitcoin (BTC 0.60%) stands as one of the most explosive investments in history. The cryptocurrency is up more than 3,900% over the past decade alone. However, the market-leading cryptocurrency has also seen a big valuation pullback and now trades down roughly two-thirds from its high.

What comes next for Bitcoin? Read on to see two Motley Fool contributors outline bull and bear cases for the world's most valuable cryptocurrency. 

Stacks of Bitcoins.

Image source: Getty Images.

Bull case: Bitcoin is a pillar of long-term strength

Anders Bylund: I'm not a Bitcoin maximalist. In my eyes, every portfolio benefits from a healthy amount of diversification. In my own cryptocurrency collection, for example, Bitcoin accounts for just 27% of the portfolio's total value today.

However, Bitcoin plays a specific role in my crypto holdings, and it's a no-brainer move to build your long-term crypto investments around this pillar of strength.

Bitcoin has proved its mettle over the years. What started as a small experiment in secure digital bookkeeping has proven its resilience against hacker attacks and rival cryptocurrencies. Many of the largest crypto rivals on the market today started life as clones of Bitcoin's code, only tweaking a few of the system's key parameters. For example, the popular Dogecoin cryptocurrency is a clone-of-a-clone of Bitcoin, running a different mining algorithm and lacking the Bitcoin's lifetime limit on the number of digital coins in existence.

Joke currencies like Dogecoin should fall by the wayside over time because they were explicitly designed to be worthless in the long run. By contrast, Bitcoin's stingy design parameters add up to a clumsy payment processor but a potentially solid vehicle for storing monetary value over the long term.

The hard-coded limit of 21 million Bitcoins ensures that the cryptocurrency will be scarce for the long haul. The last coin should be mined before the year 2140, and then the minting rewards will be replaced by transaction fees. If cryptocurrencies continue to expand their financial functionality and global reach, each Bitcoin might be worth millions of dollars by then. Experts argue that Bitcoin's total market value could exceed $300 trillion by then, compared to just $450 billion today. That's a potential gain of 67,000%. Even though the final value could fall far short of that audacious goal, the profit potential remains enormous.

So, as long as you see a future for blockchain ledgers and digital assets, it seems kind of silly to leave Bitcoin out of your portfolio. Today's volatile youngster should grow up to become a rock-solid value platform over the next couple of decades.

Bear case: Bitcoin's value proposition is muddled

Keith Noonan: Bitcoin was originally championed by many as a decentralized payment method -- a literal cryptographic currency. However, it's never seen much actual use as a currency, and it doesn't seem to make much sense as one. Even though transaction times and fees have improved, the token is simply too volatile to make for a good medium of exchange even when immediately converted into fiat currency upon receipt. 

The popular thesis for why Bitcoin is worth holding has shifted to the token being a form of digital gold that generally appreciates in value at a much quicker pace. So long as the token price keeps marching higher over the long term, why wouldn't you want to own it? But there are elements to the decentralized store-of-value thesis that seem shaky. 

Bitcoin has been touted as a hedge against inflation and a bulwark against stock market and economic volatility. However, the token and the cryptocurrency market at large have actually come to trade closely in line with stock market moves and economic news. For instance, it seems clear the Federal Reserve's interest rate hikes have created significant selling pressure for Bitcoin.

And while the adoption of the cryptocurrency among institutional investors has helped the coin go mainstream and increased its value, it's also made the coin increasingly connected with the financial systems the cryptocurrency is still championed as an alternative to. With Bitcoin becoming increasingly integrated into the broader financial system, the risk of regulation has also increased. 

The main mechanism for driving the price higher seems to be FOMO: fear of missing out. That may prove to be enough to send Bitcoin's valuation surging back to new heights, and there's admittedly a great brand and dedicated community behind the token, but valuing the cryptocurrency is a speculation-heavy task.

Should you buy Bitcoin?

Bitcoin has driven the adoption of cryptocurrencies and stands as the clear market leader in the market. However, it remains a volatile and relatively high-risk investment. The cryptocurrency looks much cheaper after recent sell-offs and could still have huge upside, but you should keep your personal risk tolerance in mind when assessing whether to add the token to your portfolio.