Everyone dreams of finding the game-changing stock that carries their portfolio to the next level and keeps it there for years. These stocks are not easy to find because capitalism is ruthless, and many companies reach new heights but can't stay atop the metaphorical mountain long enough.

But what if these fantastic companies were only hard to find because you focused your search only on unproven growth stocks that may or may not work out? What if investors could just as easily look to growing companies that have already walked the walk and have room to continue growing for years to come?

Don't make things hard on yourself. Consider these two growth stocks investors can buy and hold for the foreseeable future.

1. Costco: The legend of the $1.50 hot dog-and-soda deal

Ask anyone who shops at big-box retailers where they can order a jumbo hot dog and soft drink for $1.50, and they'll probably point you to Costco Wholesale (COST 0.85%). The retailer has maintained that price since launching the deal in 1985. The company surely loses money on it, but it's an arguably legendary marketing tool that gives Costco priceless brand recognition. The company doesn't even spend on advertising!

Costco is a retailer that sells goods and services at wholesale prices in a warehouse setting. It charges membership fees for shopper access to its stores. While the company keeps the profit margins low of the products it sells, the membership dues are a high-margin, recurring revenue stream. This sales formula has worked for years, turning Costco into one of America's largest companies.

Razor-thin margins also help keep competition at bay. Costco generates just $0.02 in free cash flow on every sales dollar. That doesn't leave  much room for a competitor to undercut you.

Charts showing Costco's revenue and free cash flow rising since 1990.

COST Revenue (TTM) data by YCharts

Why invest in Costco? Because this simple business has a long growth runway ahead. Consumers drive the American economy, and they love the Costco brand. According to the 2023 Axios Harris Poll, which tracks consumer sentiment toward various corporations, Costco ranked second overall.

Financially, Costco is also robust. The company makes enough profit every quarter that it pays a dividend. The dividend yield is less than 1% (partially because the stock price appreciates so well), but the company also periodically pays out large special dividends, so that low yield is deceiving. Analysts believe earnings per share (EPS) will grow by an average of 8% annually over the next three to five years, meaning there is plenty of profit to justify raising the dividend.

For new investors a caveat to consider is that the stock trades near all-time highs on valuation and is often considered expensive. The premium price is something it earned with its reputation and strong track record. Investors interested in Costco should consider buying the stock slowly and get more aggressive on broader market pullbacks.

2. Airbnb: The new way travelers stay

The digital economy has pulled many industries into the 21st century, including travel. While many still use hotels for short-term stays, Airbnb (ABNB 3.64%) has transformed how people rent spaces by building a marketplace you can access on your phone. Traditionally, you might find quality hotels in well-populated areas and motels in sparser markets. But Airbnb solved that problem by enabling any residential property to become a short-term rental.

Airbnb isn't the only business like it, but it's arguably the most well-known. It's seemingly achieved the gold standard of marketing -- when your product becomes the fill-in word for what you sell. In other words, people don't book a room or a short-term rental for their weekend getaway; they book an Airbnb.

Chart showing Airbnb's revenue and free cash flow rising since early 2021.

ABNB Revenue (TTM) data by YCharts

Airbnb could just be getting started. The company has more than 4 million hosts and operates worldwide. The planet has more than 8 billion people, and the modern economy is becoming increasingly mobile. A remote worker can choose to stay somewhere to work one month and elsewhere the next. Airbnb's financials reflect the company's success to date. Revenue has exploded since the pandemic, and the business is already very profitable, generating $3.8 billion in free cash flow on $8.7 billion in revenue, a 43% conversion rate.

Additionally, analysts believe Airbnb will continue growing as more people travel and book experiences over the coming years. Current estimates see Airbnb's revenue more than doubling by the end of the decade and earnings per share growing by an average of 20% annually over the next three to five years. The stock trades at a forward price-to-earnings of 42, which, at a PEG ratio of 2, isn't cheap. However, long-term investors can enjoy stellar returns as the business grows into and beyond its valuation.