• Strategy, Mara Holdings, and Verona Pharma have each risen by more than 1,500% in the past five years.

• Investments in speculative cryptocurrency plays like Strategy and Mara Holdings can pay off. They can also go quite badly.

• Verona Pharma is a less speculative investment now that it has its first approved treatment on the market.

• 10 stocks we like better than Strategy ›

If you want to achieve significant gains in the stock market, you'll probably want to plan to hold on and remain invested for many years, or even decades. But in some cases, big payoffs can come much faster than that. The benefit of investing in growth stocks is that they have the potential to deliver some terrific returns.

For example, growth stocks Strategy (NASDAQ: MSTR), Mara Holdings (NASDAQ: MARA), and Verona Pharma (NASDAQ: VRNA) have yielded fantastic gains for investors over the past five years. If you had invested $15,000 into each one of these stocks just five years ago and held on, you would have a portfolio worth more than $1 million today. The question is, do they still have the potential for further significant gains for investors who buy them right now?

A $15,000 investment made five years ago into the company that at that time called itself MicroStrategy would now be worth around $458,000. That's a staggering return when you consider that its core technology business hasn't been taking off. The company, which earlier this year shortened its name to Strategy, has actually experienced a decline in revenue in recent years. While it's nominally involved in providing business intelligence solutions, the reason its stock skyrocketed was tied to its aggressive moves in the cryptocurrency space.

Strategy is the largest corporate holder of Bitcoin (CRYPTO: BTC), with a stash that now totals more than 500,000 coins. The company routinely updates investors on its position and Bitcoin holdings. Executive Chairman Michael Saylor is incredibly bullish on the popular digital currency's potential value, predicting that its token price will climb to well over $1 million in the future, and suggesting that it could potentially top $13 million by 2045.

Strategy stock could still rise higher if Bitcoin does well. But it's a highly speculative buy: Its valuation is not tied to its overall performance, but is instead contingent on how strong the crypto market is. If you're bullish about that, you may feel that the stock could be a good buy. But for the majority of investors, this investment is likely to be too risky and speculative to hold.