He's a generational talent who signed a $30 million rookie contract.
I know guys who played in the NFL and they got paid a sliver of that, at best. They are out of the league. 99% of guys who make it aren't Saquon Barkley. Shit, 99% of guys in his position aren't at his level. RBs do not last at the NFL level for very long. There's always some young new hotshot out of the college game who is faster, younger, and not beat up.
The big issue is that most of those guys spent their entire lives to that point to play in the NFL. They didn't challenge themselves in high school or college from an academic standpoint - they focused on football. They took home through that 3 year rookie deal MAYBE $200k-300k total after tax, outside training expenses, agent expenses, etc.