NFL star Kirk Cousins earns $24 million a year and spends summers in his parents' basement

This NFL starting quarterback drives a dented van he bought from his...

Washington Redskins quarterback Kirk Cousins earned $19.9 million last year and will take home $23.9 million this year. Yet the 29-year-old NFL star still chooses to live in his parents' basement during the summer.

GQ reports: "For a good portion of the off-season, the eminently practical Cousins holes up beneath the floorboards of his teenage home in Holland, Michigan. ... He shares the space with his wife, Julie."

The couple move to a warmer climate during the first few months of the year: The basement of Julie's parents' home in Georgia. "It works well," Cousins tells GQ. "We don't pay rent."

They do plan on eventually moving into their own place. After waiting to make sure they were in a good financial position to invest in real estate, Cousins and his wife bought a lakefront property this winter on which they're building a four-bedroom home.

Washington Redskins quarterback Kirk Cousins
Wesley Hitt | Getty Images

Cousins' frugal habits, which also include driving a dented GMC Savana passenger van that he bought from his grandma for $5,000, highlight an important money lesson: Just because you earn a big paycheck doesn't mean you have to, or should, become a big spender.

As earnings go up, purchases tend to go up as well, until we succumb to lifestyle inflation: living up to the ceiling of what our income will allow.

It's a trap that anyone can fall into, even those earning six figures.

"Whether you're making $50,000 a year or $200,000 a year, we all have challenges saving," money expert at Intuit Kimmie Greene tells CNBC Make It. "Because oftentimes what happens is, when people make more, they end up spending more."

As a result, many Americans are behind on saving. A good rule of thumb is to live below your means, like Cousins — not at or beyond.

To keep more of what you earn, check out:

Like this story? Like CNBC Make It on Facebook!

Don't miss: NFL player who lives on $60,000 a year says this book changed his mindset about money

Stephen Curry, LeBron James and other NBA champs are investing in start-ups