Rob Gronkowski, who hasn't touched his NFL money in 8 years, finally splurged on his first 'luxury'

Rob Gronkowski
Tom Szczerbowski | Getty Images

NFL star Rob Gronkowski revealed in his 2015 book, "It's Good to be Gronk," that he hasn't touched "one dime of my signing bonus or NFL contract money." Instead, he's been living off of his endorsement money since his career started in 2010.

On a new episode of UNINTERRUPTED's "Kneading Dough," hosted by Maverick Carter, Gronkowski confirmed that he still saves a full 100 percent of his NFL salary, which has been as high as $4 million in 2017. He's not a big spender, he added: "I'm an easy kind of guy. I can live easy."

But after eight seasons of being careful, the Patriots tight end finally splurged on a big-ticket item. "When I signed my incentive deal last year, my friend had a chain and I was like, 'Dang, man, that's a nice chain.' I never had jewelry in my life. He let me wear it last year at a party and it made me feel good," he told Carter.

"So then, in the back of my head, I said, 'If I hit all my incentives, if I do everything I need to do, get all my bonuses, put all the work in, I've gotta finally treat myself. It's been eight years. I haven't really bought anything in my career, don't really have anything luxury like that.'"

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After a productive 2017 season that ended with 1,084 yards, eight touchdowns and another Super Bowl appearance, "I finally went out and bought myself a chain," said Gronkowski. He pulled out the diamond necklace to show Carter. "And I love this puppy. … Now I know why people got jewelry. Now I understand why."

Gronkowski is far from the only athlete who enjoys spending on jewelry. Tennis star Venus Williams says it's her one guilty pleasure. And U.S. Olympic figure skater Adam Rippon told CNBC Make It that his big pre-Olympic splurge was a $6,000 gold Cartier Love Bracelet.

The NFL star still leads a relatively frugal lifestyle. After all, "when you're playing six months of the year, you're just driving home and driving to the stadium and you're not really doing anything out and about," he told Carter. As for his one "broke habit," that involves his wardrobe: "If I like the clothing, if I like the shoes, I'll wear those shoes and I'll wear that clothing down to the rags."

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Venus Williams saves most of her prize money—but she has one guilty pleasure
Venus Williams saves most of her prize money—but she has one guilty pleasure