In today’s world, there are countless flashy avenues to billionaire status. Whether it’s cryptocurrency, the AI boom, betting apps, biohacking, modern warfare, or social media, fortunes are being made at breakneck speed. Just last week, two Stanford dropouts joined the ranks of the youngest billionaires, thanks to their groundbreaking and controversial prediction platform, Kalshi.

While these modern avenues to wealth are undeniably exciting, there’s still room for joining the billionaire club with a much simpler approach. Consider a business that eschews venture capital, ignores the cash-burning race for “hypergrowth,” and focuses instead on manufacturing. This kind of business sells a product for slightly more than its production cost—a product that everyone uses, without any promises of enhancing intelligence, wealth, attractiveness, or longevity. It’s a product that does one thing: keeps car interiors clean by protecting them from dirty shoes.

This product is the unassuming automobile floor mat, and the company behind it is WeatherTech. Chances are, you encounter a WeatherTech product every time you step into a car.

WeatherTech is the brainchild of David MacNeil, a name you may not recognize. And if you were to search for his image, you wouldn’t find one on Getty Images.

David, a college dropout, was working as a car salesman in the late 1980s when a trip to Scotland changed everything. During his vacation, he rented a car and was struck by the high-quality rubber floor mats, designed with a raised edge to capture water and debris. This sparked an idea.

Returning home, David contacted the English manufacturer and struck a deal to import a 20-foot container of these mats to the U.S., financing his venture with a second mortgage on his home. He named his enterprise WeatherTech. In its early days, he ran the business from his garage in Clarendon Hills, Illinois, with the company’s 1-800 number linked to his home phone. Calls from Europe? He took them, no matter if they came in at 3 am.

• He made $40,000 in 1991
• He made $160,000 in 1992
• He made $400,000 in 1993

As the business grew, David pivoted from importing someone else’s product to making his own. And that’s where he struck gold.

In 2025, WeatherTech will earn $800 million in revenue and generate around $200 million in profits. And as the company’s sole owner, 100% of those profits flow to David. Based on any reasonable multiple of EBITDA, there’s no doubt that David is a billionaire. By our count, David MacNeil’s net worth is a MINIMUM $2 billion. And yet, you won’t find him profiled by Bloomberg or Forbes as a billionaire.

Despite his under-the-radar success story, there have been some signs of David’s success over the years.

In 2018, MacNeil made international headlines when he purchased a 1963 Ferrari 250 GTO for $70 million. The purchase set a world record for the most expensive car ever sold at the time.

And then there’s this week’s news.

The Wall Street Journal just revealed that David paid $75 million for a sprawling ocean-to-Intracoastal megamansion in the tiny, ultra-wealthy town of Manalapan, Florida. And this wasn’t just any random estate. The property sits on land once owned by Billy Joel, who sold the 1.94-acre parcel back in 2018 to a retired businessman named Frank Mennella. The Mennellas spent several years and a small fortune constructing a 16,000-plus-square-foot, hotel-style modern compound complete with a bowling alley, movie theater, spa wing, billiards room, 1,000-bottle wine cellar, private dock, and a tunnel that runs under Highway A1A to an oceanfront cabana.

They listed the finished property this past May for $84.888 million. And now David MacNeil is under contract to buy it, fully furnished, for around $75 million. Here’s a video tour:

And here’s the wild part: This is not David’s only footprint in Manalapan. Not even close.

Over the last two years, he has quietly spent $94 million buying two other massive land parcels about a mile away. His original plan was to combine them into a single megamansion build.

Add it all up, and David MacNeil now owns roughly $170 million worth of real estate in Manalapan alone.

The reason for this latest purchase is surprisingly down-to-earth. David’s daughter, who lives in nearby Wellington, is expecting a baby. He wanted to be closer for the birth and the early years, and the Mennella estate offered something no ground-up construction project could match: the ability to move in immediately.

Most buyers spend years trying to secure even a single waterfront parcel in Manalapan. David MacNeil now controls three. One is a move-in-ready, hotel-style compound built on Billy Joel’s former land. The other two are prime ocean-to-lake parcels so desirable that he’s casually offering them for $125 million while deciding whether he even wants to sell.

Most billionaires announce their wealth through tech IPOs, viral apps, crypto booms, or splashy venture-backed moonshots. David MacNeil? He did it by selling rubber floor mats. And today, nearly four decades after answering WeatherTech customer calls from his garage, he’s one of the most powerful — and least publicly known — real estate players in one of Florida’s most exclusive ZIP codes.