Connors was a relentless p****, and Mac was an entitled brat. Nastase was simply a despicable cheater. What is different with them is that all three had the innate drive to compete in order to succeed. That, however has a completely different background than what Nick has. They had to actually fight for their wealth much more than Nick has and so the connection between their winning and wealth was more direct. They actually realised that they are in a unique position and the only thing separating them from being where they want to be is their competition.
Nick isn't per se a bad character. He is just very typical for his time and a bit spoiled from all the easy money from an early age. Somehow the connection between his winning and the massive wealth is lost on him, because he started to get serious money from an early age, and maybe he also had small expectation when he first started out, so he can't quite visualise what he "leaves on the table" as Roddick put it some time ago. One can very well see it that his shenanigans are mostly related to himself. However, in later years being often confronted by others about complex issues related to his social interactions he started to get sensitive about problems related to justice and so started to look much more seriously on what is going on the tour, hence his pretty intense criticism of some of the problems there (mostly related to privileges and lack of uniformity of the application of the rules of the sport).