Invest in the right stocks, and $5,000 could be the beginning of something big. Stocks are great wealth-building tools, but it's important to ignore the short-term price movements and focus on the performance of the business itself, as that is the most reliable way to make money in stocks over the long term.

With that said, here are three great stocks to buy if you have some spare cash to invest.

Invest in the growth of streaming with Roku

Someday, all traditional TV programming will be streamed. That's what Roku (NASDAQ:ROKU) believes, and it's well-positioned to benefit from this megatrend. Roku is one of the leading streaming platforms in the U.S., and its recent operating results are pointing to a big market opportunity.

Three one hundred dollar bills nestled in the branches of a Christmas tree.

Image source: Getty Images.

Roku has benefited tremendously from the success of streaming services like Netflix (NASDAQ:NFLX) and Walt Disney's (NYSE:DIS) Disney+. More users continue to join Roku, which drove platform revenue up 78% year over year in the third quarter. Sales of Roku players continue to grow, which is contributing to robust growth in new users, but most of the company's revenue comes from advertising, subscription services, and other commerce transactions over its platform. 

Netflix and Disney are good places to invest, too. Netflix has 195 million users and is still growing strong, and Disney just announced a significant ramp in its investing plans for Disney+, which has already reached 86 million subscribers. 

But Roku might be the best streaming stock overall since it allows users to conveniently access dozens of streaming services on a single platform. Roku's advantage is that it is pre-installed on nearly a third of all smart TVs sold in the U.S., and it's a valuable partner for content distributors and advertisers who use Roku to delivering relevant ads to users and, in return, increase engagement on Roku's platform. 

An investment in Roku is a bet on the growth in streaming. With Netflix, Disney+, Apple TV+, and a host of other services continuing to prosper in a new era of digital entertainment, Roku is one of the best growth stocks to hold for the next five years and beyond.

Wayfair is filling a big void in e-commerce

While Amazon dominates e-commerce for many retail categories, Wayfair (NYSE:W) has quietly carved out a niche as the leading online destination for home goods. It has invested heavily in its CastleGate logistics network, which is specifically designed to deliver large, heavy items in a timely manner. 

Most items are shipped directly from Wayfair's network of 12,000 suppliers, which allows Wayfair to hold minimal inventory and direct more investment to technology and building more CastleGate facilities to stretch its lead in the market. 

Wayfair has built a sophisticated platform for selling items for the home, with its mobile app and vast selection of millions of items across different price points. Revenue growth accelerated in 2020, reaching 66% in the third quarter. While we'll have to wait and see whether Wayfair can sustain these high growth levels once the coronavirus is behind us, Wayfair can deliver above-average growth for a long time. For instance, in 2019, revenue grew 34% year over year, which is still enough to fuel big returns for investors.

At $13 billion in trailing-12-month revenue, Wayfair is just scratching the surface of its potential in a market that management estimates will approach $1 trillion by 2030. 

Hasbro is positioned for a recovery

Hasbro (NASDAQ:HAS) has a leading portfolio of toy brands such as Nerf and Transformers, but its Disney partnership to make licensed Star Wars toys has been one of its best sellers lately. The growth of Disney+ is driving higher engagement among kids, which could drive healthy sales through the holiday quarter for Hasbro's partner brands segment, where sales have fallen 10% year to date compared to 2019. 

Overall, production delays for Hasbro's film projects dinged revenue growth in the third quarter, but the stock price has been drifting back to 2019 highs as the company posted a sequential improvement in revenue growth.

HAS Chart

HAS data by YCharts

Consumer demand was strong for Hasbro's core brands such as Monopoly, Play-Doh, and Magic: The Gathering. Revenue from franchise brands increased 4% year over year in the last quarter, and management likes the position it's in heading into the all-important holiday quarter.

As it closes the books on a challenging year, Hasbro's production at third-party factories is back to normal operations, and the company has a range of new products releasing for the holidays. 

The return to full strength for Hasbro's Entertainment One business is also a catalyst to watch in 2021. It shouldn't be too long before Entertainment One's film projects resume, especially with the recent approval by the U.S. Food and Drug Administration for the emergency use of the COVID-19 mRNA vaccine from Pfizer and BioNTech

With the stock price down, this is an ideal time to invest in one of the leading toy brands. Hasbro continues to invest in digital games and other initiatives that could be significant sources of growth over the long term. 

Your edge against Wall Street

While no one knows with certainty how stocks, in general, will perform in 2021, just remember that your advantage over the big firms on Wall Street is time. If you plant a seed in a growing company and regularly add shares to that holding over time, you're stacking the odds significantly in your favor of earning a satisfactory return.

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.