When you buy a stock, you're buying a stake in a business. Would you, then, invest your hard-earned money in a company that might not be around a couple of decades from now or might barely grow over the years?

If your answer is a resounding no, you understand why it's essential to identify businesses with sustainable competitive advantages and strong growth catalysts to be worth your money. When held for really long terms, stocks of such businesses can grow manifold and help you retire rich -- something every investor would aim for.

These three Motley Fool contributors believe Home Depot (NYSE:HD), Visa (NYSE:V), and Amarin Corp. (NASDAQ:AMRN) are three such great stocks you can buy and hold for decades. Here's why.

Building a rich future

Rich Duprey (Home Depot): Walk into any Home Depot home-improvement center, and with all the lumber, construction materials, and garden supplies, you don't get the sense that this is a big-time tech company. This is a business in which you're working with your hands and wiping sweat off your brow. Yet the investments Big Orange has made in its business have indeed created a technological wonder.

Home Depot's online operations are the fourth-largest of all online retailers, generating some $6.7 billion in annual sales for its website and influencing 60% of its total sales, whether online or in store. It also continues to invest, pledging to spend $11 billion over the next three years in its stores, on its online and IT platforms, and in unifying its supply chain, all in a bid to improve the customer experience.

Step of coin stacks with a clock in the background.

Image source: Getty Images.

By spending big internally, the DIY big-box store's returns have crushed those of rival Lowe's (NYSE:LOW). Home Depot has generated more than 940% in total returns over the past decade compared to a 482% increase at its blue-bannered rival. Lowe's is now having to play catch-up with Home Depot and is hoping Marvin Ellison, one of its rival's former executives, can achieve the goal as CEO.

Certainly there are risks involved in a Home Depot investment, for example, should the housing market crash again. But it has rewarded patient investors with quickly rising dividends and share buybacks, and the investor payout now stands at $4 a share and yields 2% annually.

Having made the tough investments early on, Home Depot is now in the enviable position of cashing in on them. Over the next few decades, regardless of which way Lowe's goes, you should expect Home Depot to continue rewarding shareholders with higher dividends and greater capital appreciation.

This trend is only set to pick up in coming years

Neha Chamaria (Visa): My colleague Rich just told you how big the online business is for Home Depot. But what would you, as a customer, require to shop online? Cashless payment modes, for sure, like credit and debit cards. You've probably already been using plastic money for years now, but did you know that nearly 80% of consumer transactions across the globe are still cash driven? That stunning fact, combined with the e-commerce boom, perfectly positions Visa for growth for decades to come.

As the largest payment-processing company in the world, Visa already has an unbeatable foothold in a high-potential industry. As more merchants across the globe start accepting virtual payments and cards, more banks will issue Visa-branded cards, adding layer after layer to the company's business and brand value. And every time someone swipes a Visa card, the company will make money off it in the form of transaction and volume fees.

As of the quarter ended March 2018, Visa had nearly 3.3 billion cards in circulation. B2B, or business-to-business payments, is another huge emerging opportunity. In short, Visa makes for a no-brainer stock to hold for decades as digitization picks up globally. The company enjoys a solid net profit margin of 30% or higher, one that looks sustainable given the growth potential for its products and services. For long-term shareholders, the returns should be twofold: higher dividends and share repurchases backed by bountiful cash flows, followed by appreciation in Visa's share price.

The best is yet to come

George Budwell (Amarin Corp.): Ireland's Amarin Corp. quite literally shocked Wall Street last month. As a brief recap, the company reported that its prescription fish oil pill, Vascepa, produced a 25% relative risk reduction in serious cardiovascular events (heart attack, stroke) in patients already taking statins -- an unprecedented result for an omega-3 supplement of any kind.

Immediately thereafter, the stock got a slew of upgrades from analysts, along with a number of handsome new price targets. Citi, for instance, suggested that the stock could touch a jaw-dropping $50 per share within the next year. As a result, Amarin is arguably turning into a must-own equity for long-term biotech investors.

The core reason is that Vascepa now stands a real shot at becoming an integral part of the standard of care for patients at risk of serious cardiovascular events despite being on statin therapy. That's a massive market that should easily drive Vascepa into megablockbuster (sales greater than $1 billion a year) territory in the next decade. 

Of course, the Food and Drug Administration will ultimately have the final say on Vascepa's future commercial opportunities. But the odds now seem stacked in the drug's favor. Not only does Vascepa appear to be a truly effective therapy based on these compelling top-line results, but the drug is also notably cheaper than alternative cholesterol-lowering therapies such as PCSK9 inhibitors. This potent combination of clear-cut efficacy and an appealing price tag bodes well for the drug's upcoming regulatory review. 

Bottom line: Amarin, as a company, is set to grow by leaps and bounds in the coming years, thanks to Vascepa's breakthrough in this high-value market.  

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.