Forget business services and banking: The next wave of billion-dollar companies are taking the old sectors and turning them on their head.

This year's 30 Under 30 honorees hail from cities across America, but they all have one thing in common: a desire to effect change, and the ability to generate serious cash. To do so, they're looking at industries as varied as satellite services and sustainable energy.

Here's a look at the most promising industries for young entrepreneurs today:

1. Good money.

Consumers are increasingly leery of doing business with traditional banks. Indeed, the share of the U.S. population expressing confidence in financial institutions continues to lag at just 30 percent--for the eighth consecutive year after the 2008 recession, according to a 2016 Gallup Poll. Meanwhile, the financial technology sector--including startups that use technology to process, manage, or create new funds--is continuing to attract VC dollars: In 2016, fintech companies raised as much as $12.7 billion across more than 800 deals, according to CB Insights data.

Millennial founders are seizing on this market opportunity, aiming to give more (younger) customers the ability to, for instance, invest in commercial real estate. Cadre, a real estate investment company, is using technology to make this cheaper: On the site, users can find statistics and information on a property's value. Of course, you still need to be fairly well-off to invest. The minimum stake rings in at a couple hundred thousand dollars, not including an upfront fee and subscription rate, though Cadre claims it's saving customers 50 percent of what they'd pay a typical fund. What's more, deals can be completed in a matter of weeks, as opposed to months.

"The asset class is so powerful in how it can shape people's futures, but it's only accessible to a small subset of our population," explains Ryan Williams, 29, the company's co-founder and CEO.

There's also Robinhood, the San Francisco brokerage that lets users buy and sell stock via a smartphone app. The company's 30-year-old co-founder and co-CEO, Vladimir Tenev, wanted to make it easier for Millennials to grow their wealth without breaking the bank. The startup is commission-free, though it intends to generate revenue by charging for extra features on a subscription service, called Robinhood Gold.

2. Clean food.

As customers grow increasingly health-conscious--shelling out millions annually for, say, fitness trackers or green juice--a growing number of startups are finding opportunity in the business of food. The number of global food and beverage company launches that claim to be vegetarian or vegan was up 60 percent between 2011 and 2015, according to Innova Market Insights, a business services and research firm. Meanwhile, U.S. consumers spend more than $43 billion on organic food, according to data from the Organic Trade Association.

This year's 30 Under 30 are generating revenue by providing natural, clean, and relatively inexpensive alternatives to existing food products. By Chloe, for instance, is a network of restaurants serving plant-based dishes such as Peanutty Kale, which consists of raw kale, red onion, crushed peanuts, and peanut sauce ($6.95.) The company brought in $10 million in 2016, and expects to bring in $30 million by the end of this year. Then there's Nomiku, a startup that makes Wi-Fi-enabled cooking devices for $250. With sous vide, co-founder Lisa Q. Fetterman explains, users can heat vacuum-sealed food in a low-temperature water bath, helping to preserve flavor and texture.

3. Moon shots.

As Elon Musk and Jeff Bezos continue on their quest to go to the moon and beyond, the aerospace and defense industry is on the rise: In the U.S., it generated some $608 billion in revenue in 2015, according to the Aerospace Industries Association, and sales continue to grow by roughly 2 percent annually.

That trend is also reflected on the 30 Under 30, as entrepreneurs across the country tackle satellites, drones, and renewable energy. Boston-based Accion Systems, for one, develops advanced satellite propulsion systems for the space industry; it's named after the summoning charm that Hermione Granger taught Harry Potter at Hogwarts. Rocket-scientist co-founders Louis Perna and Natalya Bailey generated an impressive $4.5 million in revenues on these devices last year. Below earth orbit lies the purview of Aerobo, a movie studio that employs aerial cinematography and drone services, and that became the first operator in New York State to be approved by the Federal Aviation Administration. It's the brainchild of Brian Streem, 29, a graduate of NYU's film program.

Meanwhile, Modern Electron wants to end our dependency on traditional power plants through thermionic converters. The startup, launched by 27-year-old co-founder and CTO Max Mankin, makes generators at a much lower cost by using the same supply chain as semiconductor chips.

It seems Musk and Bezos aren't the only ones making both real and proverbial moon shots.

4. New marketing.

Any advertiser will tell you that the younger generation is notoriously difficult to pin down. According to a 2015 study from Microsoft, consumers generally lose concentration after eight seconds, thanks to the ubiquity of digital information. (To put that into context: A goldfish can concentrate for nine seconds.) "Heavy multi-screeners find it difficult to filter out irrelevant stimuli--they're more easily distracted by multiple streams of media," the report said.

To that end, young entrepreneurs are increasingly looking to what's known as influencer marketing: tapping social media "celebrities," like Michelle Phan or The Fat Jew, and commissioning them to promote a product that reaches millions of daily viewers. That's how Karen X. Cheng, 29, stumbled on the idea for her business. After quitting her job at Microsoft, Cheng posted a video on YouTube in which she performed a parody of the song "American Pie." The video soon went viral, and she parlayed that savvy into a marketing firm that now offers both consulting and video creation services for clients such as Beats and Credit Karma.

Still others are launching businesses that help advertisers to measure the return on their investment: Appboy, for instance, makes targeting tools for small businesses, and counts clients including, Delivery Hero, and SoundCloud. TrackMaven, another service firm, lets companies track how their TV, social, digital, and traditional media campaigns drive traffic to their websites.

5. Assisted living.

The Internet of Things market is expected to account for as much as $267 billion in spending by 2020, and as technology giants including Amazon and Google continue to invest in digital assistants, the next generation of entrepreneurs is similarly betting on the technology. Thalmic Labs, based in Kitchener, Ontario, for example, makes an A.I.-infused armband that measures electrical signals in wearers' muscles and enables them to control phones and laptops. The company, run by 27-year-old co-founder and CEO Stephen Lake, recently received investment from Amazon (in total, it's raised $135.6 million.)

Then there's Rad Power Bikes, a Seattle e-bike business that generates more than $30 million in revenue; the device "captivates the people who believe in exploring alternative energy," explains co-founder and president Mike Radenbaugh. Neopenda, a startup that makes a wearable to monitor vital signs for newborns, has similarly seized on technology to save the lives of infants.

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