It was intended as a snarky jab at MJ because he apparently has a gambling addiction
Very PC of him
More than just that.
MJ was smeared when his father was murdered because of his "gambling addiction". His first retirement was also smeared as a secret league ban because of his gambling. Both are complete horseshit. MJ has a competitive addiction and not a gambling addition. While the sums he gambles regularly are large, he has so much wealth it is little more than you or I play quarter pot Poker with buddies.
Is he a jerk? Unless you are his teammate who he's trying to maximize potential with or opponent who he is trying to crush, most likely not.
Is he rich? Filthy rich and he's earned every penny. He made the NBA Global and made Nike the powerhouse they are today.
There are deeper seeded issues with MJ being larger apolitical during his playing days and once uttering the line that "republicans buy sneakers too". He caught heat for that then and many wish he'd be more like Lebron in his activism. To his credit, he says he wished he could re-do some of that but his focus was being the best basketball player on the planet and winning games. He wasn't well versed in politics and it wasn't a major focus of his to understand or speak on such subjects. And now after saying he wished he would have used his platform differently, something happened, he donates only to get slapped by some try hard white dude who has done zero to progress race relations in our country.
TLDR: Schreier was trying to get some e-cred from the few people on twitter he doesn't have blocked and tried to dunk on MJ. Good move there, chief.