I think that Ramit Sethi came up with one of the best titles ever with his best-selling book, I Will Teach You to Be Rich. Practically everyone wants to be rich (or at least, richer than they are). Most people, though, don't know how to achieve that goal. Sethi helps them do it by laying out specific steps to take.

One simple way to become richer is to invest in the right stocks. Granted, there's always a chance that even great stocks will go down instead of going up. But well-run businesses will take the steps necessary to increase their long-term valuations, whether or not their share prices reflect that higher valuation yet. 

Investing in these kinds of businesses is a surefire way to increase your net worth. With that in mind, here are three stocks that I'm confident will make you richer in 2021. 

Smiling young man and woman holding cash in their hands

Image source: Getty Images.

1. Brookfield Renewable

I don't know if there's more of a slam dunk right now than renewable energy stocks. And Brookfield Renewable (NYSE:BEP) (NYSE:BEPC) ranks as one of the best renewable energy stocks on the market.

Let me explain my optimism. During the coronavirus-caused recession last year, renewable energy generation increased while overall electricity generation in the U.S. fell. Why did that happen? For one thing, wind and solar power is now more cost-effective than fossil-fuel alternatives. At the same time, there's a concentrated push across the world to reduce carbon emissions. That means countries and companies are turning to renewable power.

Now let's talk about Brookfield Renewable. The company operates hydroelectric, wind, solar, and storage facilities throughout four continents. These facilities can generate a whopping 19,000 megawatts of electric power. Here's the kicker: Brookfield Renewable's development pipeline includes another 18,000 megawatts of capacity.

The company says that it will deliver long-term annual returns of close to 15%. It's done even better than that over the last two decades. With the incoming Biden administration committed to reducing U.S. carbon emissions, I think Brookfield Renewable is in the exact right place at the right time to make investors richer in 2021 and beyond.

2. Square

You'd think that 2020 would've been horrible for Square (NYSE:SQ). Small- and medium-sized businesses (Square's core customer base) faced huge business disruptions because of the COVID-19 pandemic. To be sure, Square experienced the effects of those headwinds.

However, Square's business grew rather than shrank during the pandemic. The company delivered year-over-year revenue growth of 140% in the third quarter of 2020. Its stock skyrocketed 248% last year.

There were two primary drivers behind Square's impressive performance. The company's sales of bitcoin exploded, accounting for over half of its Q3 revenue (but a much smaller portion of total gross profit). Square's peer-to-peer payment app Cash App also delivered tremendous growth beyond bitcoin sales.

Both bitcoin and Cash App are here to stay. I think that Cash App, in particular, will become even more popular in 2021 than during the heyday of the pandemic last year. 

But don't forget Square's core payment-processing business. I expect that this business will rebound solidly this year as COVID-19 vaccines roll out and people grow increasingly more comfortable shopping in stores. I have no doubt that Square will become a much more valuable company in 2021.

3. Trupanion

Of all the long-term impacts of the pandemic, I think one of the most overlooked is the increased ownership of pets. The adoption of dogs especially soared as many people worked at home and sought companionship. My view is that Trupanion (NASDAQ:TRUP) will benefit from this trend over the long run.

Actually, Trupanion is already benefiting. The company offers medical insurance for cats and dogs. Its revenue jumped 31% year over year in the third quarter of 2020.

Trupanion is truly only scratching the surface of its opportunity. The pet insurance markets in North America are way underpenetrated, with only 1% of U.S. pets and around 2% of pets in Canada covered by medical insurance. By comparison, 1 out of 4 cats and dogs in the U.K. have medical insurance.

I suspect that Trupanion will really hit its stride this year. Big supplemental insurance company Aflac bought a $200 million stake in Trupanion in October. Importantly, Aflac will offer Trupanion's pet insurance with its other insurance offerings to employees in workplaces across the U.S. This should be a major boost for Trupanion's business. With the company's market cap at around $4 billion, the stock should have plenty of room to run.

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.