For more than three months, investors have had their resolve tested like never before. This isn't to say that we haven't seen stock market corrections or recessions in the U.S. economy before, so much as to point out how abruptly the rug was pulled out from beneath investors. The coronavirus disease 2019 (COVID-19) pandemic ultimately took just 33 calendar days to wipe out 34% of the value for the broad-based S&P 500.

The great news for investors is that panic usually breeds opportunity, as long as you're willing to take a long-term approach. Though you might see get-rich-quick offers as advertisements while researching stocks or surfing the internet, the easiest way to get rich (and with the least amount of hassle) is to buy game-changing businesses and hang onto these stocks for long periods of time. It's truly amazing what time can do for a patient investor.

Best of all, you don't need a mountain of capital to get started investing in the stock market. If you have $500 in disposable cash -- i.e., money you won't need to pay bills or for emergencies -- you have more than enough to put to work in these game-changing stocks.

Five one hundred dollar bills staggered neatly on top of each other.

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Pinterest

Social media might not seem like a game-changer, but for the very few companies that get it right, the business model can become an absolute cash cow. While Facebook might be the model to follow here, it's already one of the largest companies in the world by market cap. That's why Pinterest (NYSE:PINS) is the stock long-term investors should consider buying in the social media space, because it's like buying into Facebook in the early 2010s, before the real cash flow growth began.

Although Pinterest's monthly active user (MAU) growth in the U.S. could be more robust, it's the company's potential in international markets that should have investors jazzed. Over the past five quarters, Pinterest has added roughly 102 million MAUs, of which around 90% have come from overseas. Even though average revenue per user (ARPU) is substantially lower in international markets, relative to the U.S., these overseas markets also offer the greatest opportunity to grow ARPU. Personally, I wouldn't be shocked if MAU growth and increased platform engagement drove international ARPU up 400% to 500% between 2019 and 2030.

Pinterest is also shifting its platform to lean more on e-commerce. With MAUs actively sharing their interests, Pinterest shouldn't have any trouble pivoting some of these passive users into consumers. As long as it can continue to attract small-and-medium-sized businesses to its platform, Pinterest could grow into a cross between eBay and Etsy on the e-commerce front.

A veterinarian examining a small white dog.

Image source: Getty Images.

Trupanion

If there's one thing you never ever want to do as an investor, it's best against the pet industry. That's why pet insurance play Trupanion (NASDAQ:TRUP) is a no-brainer long-term investment.

According to statistics from the American Pet Products Association, total U.S. pet expenditures haven't declined on an annual basis in at least 25 years, and are estimated to make a run at $99 billion in 2020. Of this $99 billion, $29.3 billion will be spent on veterinary care and product sales, with another $19.2 billion on supplies and over-the-counter medicine. That's a boatload of cash! 

However, only between 1% and 2% of North American pet owners have insurance on their four-legged friends. Since 42.7 million U.S. households own a cat and 63.4 million own a dog, it's only logical to expect the percentage of households purchasing health insurance on their pets to rise over time. This'll be accomplished with Trupanion's targeted marketing, as well as through partnerships with veterinarians throughout North America.

The thing to realize here is that, over time, companion pets have become part of the family. A 2016 Harris poll found that 95% of pet owners classify their pet as family -- and they're likely willing to do whatever is necessary to ensure the well-being of that family member.

With much of Trupanion's business model based on highly predictable, low-churn subscriptions, and the company getting very close to recurring profitability, it's probably time for investors to throw it a bone.

A physician administering a finger prick on a young diabetes patient.

Image source: Getty Images.

Livongo Health

Another way to get rich the easy way is by purchasing and holding revolutionary health solutions company Livongo Health (NASDAQ:LVGO).

Livongo does things a bit differently than the companies already operating in the diabetes space. Livongo leans on mountains of collected data, as well as artificial intelligence, to help diabetics make smarter choices and stay in control of their disease. Though co-morbidities associated with diabetes are clearly an issue, the failure of diabetics to properly manage their disease and take regular blood-glucose reading can be just as worrisome. By eliciting behavioral changes, Livongo is helping to improve the health outcomes of its members.

The best part about Livongo's personalized health platform is that it doesn't just sound great on paper -- It's actually translated into real results. The number of Diabetes Members in its network jumped to more than 328,000 at the end of the first quarter, which is an approximate doubling from the prior-year period. Plus, since Livongo runs on a subscription-based model, its sales and cash flow tend to be highly predictable. This is how it's been able to deliver two consecutive quarterly profits, despite spending aggressively on its platform.

Of course, Livongo is really just scratching the tip of the iceberg in terms of its potential. It doesn't even have 1% of the U.S. diabetes market, as of yet, and plans to pivot its technology to assist persons with hypertension, prediabetes, and obesity live healthier lives. In short, Livongo Health has 10-bagger written all over it, if you give it the proper amount of time to shine.