It has been a tough year for investors, but the last thing you want to do now is panic. Investing is a long-term game played out over decades. Growth stocks have been hit especially hard this year, but their long-term investment thesis hasn't changed.

Shopify (SHOP -1.69%), Roku (ROKU -0.99%), and Nvidia (NVDA -0.68%) are three downtrodden companies that look like excellent buying opportunities for investors willing to hold them for the next decade and beyond. What makes these companies appealing is their position in industries due for explosive growth in the coming years.

Here's what you should know about each of these growth stocks.

1. Shopify's long-term prospects remain bright

Shopify provides people with the tools they need to run their online stores (along with brick-and-mortar operations), handling everything from payment processing to inventory management and website hosting.

The company was a huge winner during the pandemic, which shifted consumer trends online in record fashion. From 2019 to 2021, Shopify's revenue grew 192%, and the optimism around online shopping trends was higher than ever.

Shopify management expected strong trends to continue and racked up expenses in a big way this year. Revenue growth was a solid 22%, but expenses ballooned by 69% -- resulting in $2.8 billion in losses this year. The company is working to reel in costs and laid off 10% of its workforce in July.

Management may have overshot the growth of online shopping, but the company continues to grow steadily. Shopify Payments, its payment processing solution, makes it easy for merchants to accept and process payment cards. This product accounted for 54% of Shopify's total gross merchandise volume through its platform, showing room for growth.

According to eMarketer, e-commerce sales are expected to grow from $5.2 billion in 2021 to $8.1 billion in 2026, a growth rate of roughly 9% annually. One way Shopify looks to build on its position is through its Shopify Fulfillment Network (SFN). This service simplifies logistics across the supply chain, from freight to distribution to delivery, and is expected to reach scale sometime in 2023 or 2024.

While Shopify stock may be down 71% this year, it is in an excellent position to keep scaling up and taking a share of the e-commerce market.

2. Roku sits at the top of the streaming services world

Roku provides customers with a streaming platform through its various products, including Roku Stick, smart TVs, and other streaming devices. According to Conviva, a provider of video analytics services, Roku is the world's top streaming platform, with its devices streaming 30.5% of users' total viewing time. Amazon Fire TV and Samsung TV were the next closest, with 16% and 13.7%, respectively, of users' total streaming time.

Roku's platform is free to use, making most of its money from ads and revenue-sharing deals when users engage with different apps. The company was a big winner during the pandemic and put together six consecutive profitable quarters. However, it hasn't had a profitable quarter this year, and its third-quarter loss of $122 million was the largest quarterly loss in its history.

Roku faces headwinds in the short term as ad spending softens amid an uncertain economic backdrop. Many companies are concerned about the health of the economy and consumer spending and have cut back on advertising expenses in response. Roku expects its net loss to balloon to $245 million in the fourth quarter.

Roku will face volatility in the short term, but the company is in a solid position for the long haul. It has done a stellar job of growing its user base and average revenue per user. In the third quarter, its user base grew 16% to 65.4 million, while the average revenue per user was up 10% to $44.25.

Its position as the top streaming platform will be crucial to Roku as connected TV ad spending grows. According to data from Statista, connected advertising spending in the U.S. will go from $18.9 billion this year to $38.8 billion in 2026, representing an annual growth rate of 20%.

While Roku faces short-term headwinds from softening ad spending, it still sees solid growth in its customer base. The company is well positioned to ride the tailwinds as more digital ad spending shifts to connected TV -- making Roku a company that could be a huge winner over the next decade.

3. Nvidia's hardware powers lucrative innovations

Nvidia produces crucial hardware that helps push the boundaries of what is possible. Its graphic processing units (GPUs) are behind some of the most innovative technological trends, including cloud computing, artificial intelligence (AI), gaming, autonomous vehicles, cryptocurrency, and the metaverse. According to Jon Peddie Research, Nvidia recently increased its discrete GPU market share to 88% in the third quarter.

Like others, Nvidia has faced headwinds this year. Inflation has dampened consumer spending on video cards for gaming, and its inventory levels have risen rapidly. Falling cryptocurrency prices have also weighed on consumer demand. Its third-quarter (ended Oct. 30) revenue fell 12% from the prior quarter and 17% from the same quarter last year. The company predicts weakness in the fourth quarter to continue, with revenue expected to fall around 21%.

Slowing demand has weighed on the stock, which is down 43% this year. However, when you zoom out and look at the long game, Nvidia is in an excellent position to grow. The company has leveraged its technology to build platforms enabling developers to deploy AI applications or build 3D worlds and avatars for the metaverse (Omniverse platform).

Overall, Nvidia believes its total addressable markets (TAM) is $1 trillion among its multiple products. Its largest TAMs are in chips and systems and automotive technology, each estimated to be at $300 billion. These markets are followed by its AI software and the Omniverse platform products, which it marks at $150 billion each.

Nvidia stock trades at a lofty price of 37 times forward earnings and will likely face some volatility in the coming quarters. However, it's in an excellent position to capitalize on some of the most innovative technologies of our day -- making it another stellar stock that could be a huge winner over the next decade and beyond.