To begin, there's an easy answer to that question. Former professionals such as John McEnroe - who really should know better when questioning a player's character - watch with chagrin as an almost disinterested athlete makes mind-blowing money compared to those of yesteryear.
And then there's the fans, who would willingly stand in front of Serena Williams' serve to earn even a sliver of Kyrgios' ability, glaring and jeering as the Australian flames out of one tournament to the next.
In short, it's an argument of wasted talent, a career squandered. But it's pertinent to remember whose talents, exactly, are apparently being blown.
Kyrgios owes his fans nothing; they'd as soon turn on him if he suffered a prolonged slump in form. His debt to the game of tennis equals a similar amount; last I checked, the sport can survive without the 13th-ranked player in the world consistently reaching grand slam semifinals.
No, Kyrgios can use or abuse his abundant abilities how he pleases. Which brings us back to what precisely he contributes to the product of sport as entertainment.
The flood of support Novak Djokovic received after his second-round exit in Melbourne was completely justified; grace in defeat is an admirable quality. Also admirable, though, especially in an increasingly sanitised world of sport, is someone like Kyrgios, displaying erratic passion and a willingness to say something, anything, of interest.
You know, like this: "I don't really like the sport of tennis that much. I don't love it. It was crazy when I was 14 - I was all for basketball and I made the decision to play tennis. I got pushed by my parents and to this day, I can still say I don't love the sport."
Those comments from 2015 ring true with every throw of his racquet. What's a boy to do if he dislikes the only thing at which he excels?
And perhaps, for anyone keen to cast a sympathetic eye, that mentality also hints at the heart of Kyrgios' impudence. After all, anyone who has read Andre Agassi's Open will know the inner turmoil that can be felt by an athlete stuck in an isolating sport like tennis with seemingly no escape.
So we should probably be careful to condemn Kyrgios' delinquency. We have little idea why he would decide to play a 'tweener' while attempting to save the fifth set in his embarrassing loss against Andreas Seppi - but even less clue about what's happening inside his head during each point.
Labelling him a brat is reductive and, rather than driving him away from tennis, we should all be hoping Kyrgios realises his potential.
At least until he starts winning grand slams, then we can all go back to rooting against another upstart Australian.