This story is part of CNBC Make It's Millennial Money series, which details how people around the world earn, spend and save their money.

At 17, Nathanael Farrelly took his 16-year-old girlfriend's father to an Applebee's in Westerly, Rhode Island, and asked for his permission to marry her.

"Of course, his answer was no," Farrelly tells CNBC Make It.

Farrelly was hardly in a position to start a family, but the conversation pushed him to fast-track his plan to become a nurse and prove he was serious about adulthood.

To do that, he left school midway through 10th grade and earned a General Educational Development diploma, cramming two years of coursework into less than one. He later got permission to propose, and the couple married two days after her 18th birthday.

"Since meeting her, I've never questioned that," he says. "I just knew."

Farrelly became a registered nurse at 21, launched a home infusion therapy company at 24 and sold it four years later for $12.5 million — reaching financial independence before turning 30.

Now 29, he lives in Pensacola, Florida, with his wife and three children — with a fourth on the way — living off a nearly $14 million net worth. Since stepping away from full-time work in September 2024, he has been living in semi-retirement — coaching his kids' soccer team, managing his real estate portfolio and making occasional angel investments.

Here's how he built his business, retired young and started backing other like-minded entrepreneurs.

'There was no one else'

After earning his GED, Farrelly enrolled in summer classes at a local community college to become a nurse. While completing the associate's degree that allowed him to become a registered nurse, he also began work on a bachelor's — a credential often required for advancement in the field.

Farrelly became a registered nurse at 21 in 2017, and his first job was in a hospital step-down unit — a fast-paced environment not unlike an ICU. After one week of training, he arrived at work expecting to shadow another nurse, only to find his name on the assignment board with a full patient load.

"I quickly realized ... that it was not a joke," he says. "They needed me because there was no one else." His situation was not unusual. In 2017, the American Nurses Association warned CNBC of "growing shortages in different states and geographic regions" — a problem that was later exacerbated by the Covid-19 pandemic.

The stress of nursing quickly took a toll. "I remember waking up every morning nauseous ... dreading going to work," he says. "It really impacted my quality of life."

Farrelly stayed in the field, but the experience had him thinking about a different path in nursing.

Launching his own nursing business

When a classmate mentioned an opportunity in home infusion therapy, where nurses provide treatments like antibiotics or IV medications in patients' homes, Farrelly was intrigued. "I always loved placing IVs," he says.

He took a contract role and immediately saw the potential. "That opened my eyes and I realized, 'Wow, there are not enough nurses and too many patients going into the hospitals when this can be done at home,'" he says. "That's when my entrepreneurial side just expanded."​

After more than two years as an independent contractor, Farrelly launched Revitalize Specialty Infusion in March 2020, shortly after the Covid-19 pandemic hit. He funded the business with personal savings and proceeds from the sale of a home he and his wife had purchased for $140,000 and later flipped for $310,000.

Farrelly's model focused on efficiency: hiring local nurses, cutting drive times and giving nurses more control over their schedules. The start of the pandemic also proved to be perfect timing for the business, as demand for at-home nursing services surged.

"We grew a nursing team so large within just a few states, nurses were able to stay very local," he says.

This was a time when nurses were in especially high demand. While Farrelly's startup couldn't always compete on pay, the flexibility, autonomy and calmer pace drew in nurses quickly — especially those looking to leave high-stress hospital jobs.

As a result, the company quickly gained traction, with one of Farrelly's early cold calls leading to a major contract that gave him 50 patients overnight. With steady cash flow, he was fortunate to avoid taking on outside funding or debt in the early days of his business, but took out $111,000 in PPP loans in 2021, which was forgiven that year.

Going on 'family sabbatical'

In the early days of the business, Farrelly says he began getting calls from private equity firms "wanting to acquire my company for a million [dollars], a couple million," but he held off. "I knew it wasn't the right time," he says.

He decided to sell the business when he realized it couldn't keep growing on its current trajectory without outside support, and that a larger company could better support his nurses. "I started to really think about the next season of my life," he says. "I wanted to focus more on my family."

Farrelly sold Revitalize to Option Care Health, one of the largest infusion companies in the nation, for $12.5 million in May 2023. The Farrelly family moved to Florida that August, and Farrelly stayed at the company for a year and a half before stepping back to begin what he calls a "family sabbatical," joining his wife as a stay-at-home parent.

"That was the true exit for me," he says. It allowed him to "really focus on family," as well as self development, he says.

Since then, Farrelly has become an angel investor, backing a friend's coffee company and a fitness app that gamifies health metrics.

How the Farrellys spend their money

Here's how the Farrellys spent their money in February 2025:

• Discretionary: $8,021 for home and pool maintenance, furniture, medical expenses and tools
• Donations: $6,712
• Insurance: $1,950 for health, life, vision, dental, car, homeowners and flood insurance
• Property taxes: $1,862. While the Farrellys pay property taxes annually, they account for it in their monthly spending for budgeting purposes.
• Children's education: $975
• Utilities: $451 for Wi-Fi, trash, water, electricity and security 
• Transportation: $430 for Uber and gas
• Phones: $139
• Subscriptions and memberships: $104 for his gym, ChatGPT, Nintendo, VidAngel and streaming TV services

As of February 2025, Farrelly had a net worth of just under $14 million, which includes more than $5.6 million in cash, $2.77 million in stocks, $2.5 million in real estate and $500,000 in cryptocurrency.

Crypto is the riskiest part of his portfolio, but he says he started small and bought in early, back in 2016. "I accumulated my first Bitcoin at $3,000," he says. "So while it may be a roller coaster for many, anything above $3,000 is just a plus for me."

The family lives off the interest from the cash, which earns about $30,000 a month. They typically spend around half of that, with the rest reinvested.

They live in a waterfront home Farrelly purchased outright for $1.9 million, so they don't have a mortgage. Their biggest recurring costs include property taxes, insurance and private school tuition.

In February 2025, one-time expenses for home and pool maintenance, medical bills and furniture pushed their spending to just under $23,000, though Farrelly says they usually spend closer to $15,000 a month.

Looking ahead

Farrelly is focused on spending time with his family, but he could see himself launching another company down the line. He plans to continue investing in real estate and says managing his wealth carefully is a priority.

"I realized that eight figures can either last generationally or it can disappear really fast through bad investments and lifestyle creep," he says.

For now, he's protecting his savings and staying open to the right opportunity.

"My personal definition of retirement is financial freedom — not necessarily retirement from doing work that fulfills you," he says. "And with that ... I can focus on helping others and being available with my family."

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