Teladoc Health's (NYSE:TDOC) stock performance this year isn't putting a smile on its investors' faces. The shares have slipped about 30%. That's after a 138% increase last year. Teladoc's online medical visits and revenue soared in 2020 as patients opted for telehealth over in-person appointments. Now, some investors worry Teladoc won't be able to keep up the growth in a post-pandemic world.

So, we might wonder whether those who are pessimistic about Teladoc are right -- or whether the 2020 performance was just the beginning of Teladoc's story. The answer will help us determine if this stock can help you become a millionaire...

An adult and a child sit in front of a tablet as they take part in an online medical visit.

Image source: Getty Images.

Primary care and specialties

First, a little bit of background on Teladoc. The company sells its telehealth services to health plans, employers, and any organization that pays for the healthcare needs of Americans. Right now, it works with more than 100 U.S. health plans. And more than half of Fortune 500 companies have signed up for Teladoc for their employees. The company offers a vast range of services including primary care, specialties, and management of chronic conditions.

As the pandemic deepened last year, Teladoc's revenue took off. Here's a look at the company's 2020 quarterly revenue.

TDOC Revenue (Quarterly) Chart

TDOC Revenue (Quarterly) data by YCharts

And Teladoc ended the year with a 98% increase in annual revenue to more than $1 billion and a 156% increase in visits.

The arrival of coronavirus vaccines on the market late last year helped ease the pandemic in the early part of this year. If Teladoc's gains were only part of a trend linked to the pandemic, we should have seen a significant drop in visits in the first half of this year.

Instead, Teladoc continued to post gains. The second quarter is a good example. That's because the comparison period -- the second quarter of last year -- unfolded during the worst of the pandemic. In the second quarter of this year, Teladoc reported a 109% increase in revenue. That prompted the company to lift its annual revenue forecast. And Teladoc saw a 28% increase in visits.

One more clue that Teladoc's success isn't transient: The company's annual revenue already was rising prior to the pandemic.

TDOC Revenue (Annual) Chart

TDOC Revenue (Annual) data by YCharts

Growth in telemedicine

And finally, another element that supports investment in Teladoc: The general telemedicine market is growing. The global telemedicine market, at a 25.9% compound annual growth rate, is forecast to reach more than $431 billion by 2030, according to Allied Market Research.

Here's one element I think will drive Teladoc's growth: the chronic care market. The company built a stronger position in this market through its acquisition of Livongo last year. More than 40% of adult Americans suffer from more than one chronic condition. These are problems such as diabetes and hypertension.

Today, more than 20% of Teladoc's chronic care members use more than one of the service's programs. Last year, that number was 6%. And in the second quarter, the number of members enrolled in Livongo programs climbed 45% year over year to 715,000.

The acquisition of Livongo is weighing on Teladoc earnings right now. For instance, the expense of Livongo stock awards and the amortization of acquired intangibles contributed to the second-quarter net loss. But the benefits of this acquisition eventually should outweigh these near-term troubles.

Can Teladoc help make you a millionaire?

So, let's get back to our question: Can Teladoc help you become a millionaire? Today, Teladoc shares are trading close to Wall Street's very lowest 12-month share price estimate. If the stock reaches Wall Street's average estimate in that time period, it will climb 37%. Even if that happens, you would have to load up on a massive number of shares now to become a millionaire in a year. I don't think that's the right strategy.

Even if a company is solid by every measure, I don't favor making a huge bet on just one player. Instead, I prefer investing in a range of healthy companies -- and hopefully all or most of them will, over time, help you become a millionaire. Considering all I've written above about Teladoc, this innovative healthcare company could be one of them.

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.