Think 10 years is not enough time to significantly grow your portfolio? Let's look at a couple of examples where investing $10,000 would have been enough to get your portfolio to more than six figures in a decade.

Of course, these examples don't imply that things always pan out this way. There are plenty of examples of stocks that lose money over time too. But investing with a long-term mindset can pay off, and it doesn't always have to take decades for it to happen.

Both Tesla (TSLA -1.80%) and Eli Lilly (LLY -0.56%) have been 10-bagger investments during the past decade. Let's look at why these have been some phenomenal stocks to own during that stretch and see if they are still good buys right now.

Tesla

Tesla's valuation has fallen in 2024 as concerns about shrinking margins and rising competition have investors worried that the stock's elevated price is no longer justifiable. But this level of concern is nothing compared to the worries investors had regarding Tesla back in 2014. Back then, Tesla was unprofitable, and investors were concerned the company might not continue. To be at the point where the big concern about Tesla is how profitable it will be surely must be a sign of success.

A $10,000 investment in Tesla back in April of 2014 would now be worth roughly $121,460 right now -- and that's even factoring in the stock's pullback this year.

The big question, of course, is where the business goes from here. While demand for electric vehicles (EVs) continues to grow, the demand has eased somewhat and the growth in competition has led to some price depression. Competition from China is putting downward pressure on car prices. If that trend continues, Tesla's prospects for profit growth could be a cause for concern.

One underrated opportunity, for instance, involves Tesla's expanding supercharger network. Analysts believe that by the end of the decade, revenue just from Tesla's charging stations could bring in $10 billion to $20 billion in revenue. Last year, Tesla's total revenue came in at just under $97 billion, and it has more than tripled since 2020.

Trading at nearly 60 times its estimated future earnings, Tesla's stock still isn't cheap. But if you're willing to hang on for the long haul, the stock still has the potential to be a good performer given the strength of the brand and the opportunities in its charging business. And with the EV market still in its early-growth stages, there's plenty of room for the company's car sales to continue growing as well.

I doubt the stock will be a 10-bagger over the next decade, but Tesla can be a good long-term investment to hold and a way to invest in the promising EV market.

Eli Lilly

If you invested in Eli Lilly a decade ago, the odds are good that you weren't expecting the stock to be a 10-bagger. Its top-selling diabetes drug, Trulicity, wasn't approved until September 2014. At the time, antidepressant treatment Cymbalta was its top product, with revenue in 2013 totaling $5.1 billion.

Eli Lilly is a great example of how investing in an innovative healthcare company can pay off in unexpected ways. No one could have predicted that in 10 years the company would start selling the weight-loss drug Zepbound, which, along with already-approved Mounjaro (which treats diabetes), could generate more than $50 billion annually in revenue.

But just like with Pfizer's success with a COVID-19 vaccine, one of the great things about investing in a top healthcare company is that it has the potential to knock it out of the park one day with a product with massive potential. While it may seem like a company's growth prospects are underwhelming in the near term, all that needs to happen is for one successful drug or vaccine to obtain approval in a high-growth area, and it's off to the races.

That's why Eli Lilly's valuation has been skyrocketing in recent years, as investors are bullish on just how big of a game changer Zepbound may be for the business. A $10,000 investment in Eli Lilly 10 years ago would now be worth nearly $125,600. Most of those gains have come within the past two years.

Eli Lilly's stock looks expensive, trading at a forward price-to-earnings (P/E) multiple of 60. But if Zepbound and Mounjaro end up delivering their predicted incredible sales numbers, it's hard to not like the stock as a long-term investment. Plus, there's always the possibility that Eli Lilly will come out with another gem that becomes yet another growth catalyst for the business.