Supposedly Marshawn Lynch only lived off his endorsement money and socked away his NFL salary.
Another smart one was Jamal Mashburn. Per wikipedia:
Since retiring from basketball, Mashburn has worked for ESPN as an analyst and launched a number of successful business ventures. As of 2018, he owned over 90 businesses, including 34 Outback Steakhouse franchises, 37 Papa John’s franchises, and a number of car dealerships across the state of Kentucky.[12][13] Mashburn is a partner in Ol Memorial Stable, along with former Kentucky coach Rick Pitino and Outback Steakhouse co-founder Chris T. Sullivan, which owns Kentucky Derby prospect Buffalo Man.[14]
Rob Gronkowski is another one. He never cashed his game checks, just lived off of endorsements.
He’s set for life..