While monopolies may be bad for consumers, they're actually good for investors.

If you find a company that has a dominant market share, especially in a large and growing market, it's a good idea to put your money behind it. Setting aside any regulatory risks, these companies tend to have huge profit margins and wide economic moats because their monopoly status tends to block out competition. 

Keep reading to see two tech monopoly stocks that could help make you rich.

1. Airbnb: Transforming the travel industry

Airbnb (ABNB 2.77%) started as a fringe idea -- using your home as a hotel to host strangers -- but it's resonated around the world, and the home-sharing platform now has more rooms available on its platform than even the largest hotel chains.

While competition has sprung up in the home-sharing industry, namely from Expedia's VRBO, Airbnb still dominates the industry with a 74.6% market share among home-sharing platforms, according to data analytics firm M Science. Recent results show how it's leveraged that monopolistic control.

In the second quarter, the company made $711 million in adjusted EBITDA on $2.1 billion in revenue, giving it a 34% margin. Its free cash flow margin was even better at $38%, and its GAAP net margin was a solid 18%.

Airbnb is still growing fast, in part due to tailwinds from the recovery in the travel industry. Revenue jumped 58% in its most recent quarter. It's rare to find a company that is growing this fast and is still highly profitable. By contrast, most high-growth tech stocks are unprofitable because they're spending so much money to drive that growth. 

What's also remarkable about Airbnb's business model is that it spends almost nothing on capital expenditures. It spent just $11 million out of its $2 billion in operating cash flow in the first half of the year. That shows that the business essentially runs itself at this point, and the technology has scaled to the point where it can handle 6 million listings. Airbnb doesn't need to invest in more data centers, and unlike brick-and-mortar hotel chains, it doesn't own lodging properties so it doesn't need to spend money on maintenance.

Based on run-rate free cash flow this year, Airbnb stock trades at a multiple of just 17, and given its growth rate and serviceable addressable market valued at $1.5 trillion, the company looks like a good candidate to deliver multi-bagging returns. It even has the potential to grow its market cap from $70 billion today to $1 trillion.

2. Alphabet: The internet's information hub

Alphabet's (GOOG 1.25%) (GOOGL 1.27%) Google may be the first name in tech monopolies. It's been the dominant search engine around the world for nearly a generation, with roughly 90% market share, and YouTube similarly dominates its market.

Thanks to that huge market share, Google has built a formidable advertising business around search, and it has proven to be particularly resilient at a time when social media platforms are getting hammered by Apple's ad-tracking restrictions. 

In the second quarter, the company's operating margin was 28% as it reported $19.4 billion in operating income on $69.7 billion. Its Google Services business, which includes Search, YouTube, and other advertising businesses, is even more profitable, generating a 36% operating margin.

With a market cap of over $1 trillion, Alphabet doesn't have the same upside potential that Airbnb does, but it makes up for that in valuation. The stock trades at a price-to-earnings ratio of 18.4, the cheapest it's been in nearly a decade, and the same P/E ratio as the S&P 500, which makes Alphabet look like a bargain -- it's growing faster and is much more profitable than the average S&P 500 stock.

While a recession is likely to weigh on advertising demand, the company's long-term prospects look bright, and there's always the potential for Alphabet to strike gold with one of the businesses in its "other bets" segment such as its Waymo autonomous vehicle business or its biotech arm, Calico.

Even without a breakthrough in other bets, the advertising business alone could drive the stock to double in just a few years. If you're looking for a stock that's almost guaranteed to make money, Alphabet looks like a great choice.