Here's a depressing thought: some day Nick Diaz will stop fighting.Some day, either from the ravages of age, the allure of outside interests, or maybe just a growing distaste for the sport and all its inhabitants, Diaz will take his defiant sneer and his expletive-laden sound bytes and leave us behind.Whether we realize it yet or not, that's going to be a sad day for MMA. Maybe a better way to put it is, it's going to lead to a bunch of boring days thereafter. Because when you stop and think about it, there may be no more original -- between his interviews, antics, and actual athletic performances -- or more entertaining fighter in the entire sport.Diaz is a rare creature in the world of pro sports. It's not just that he says what he thinks – plenty of athletes do that, or at least have carefully cultivated that appearance. But unlike a Chael Sonnen , who simply says the most outrageous thing he can think of with a pro wrestling-style nod and wink, Diaz seems to really believe it.Of course, just because you believe what you're saying doesn't necessarily mean it's true, or even that it makes a whole lot of sense. Consider last week's Strikeforce conference call where Diaz griped that while Manny Pacquiao and Georges St. Pierre make millions, he's "over here driving a Honda because my sh-t's breaking down."This is the same Diaz who made a disclosed total of $100,000 to beat Marius Zaromskis last February. It's also the same Diaz who co-owns a gym in Lodi, California (which, from what I could tell during a recent visit, seemed to be thriving), and the same Diaz who just signed a new contract with Strikeforce. No disrespect to Honda, but it seems as if he ought to be doing a little bit better, and if not then he needs to take a hard look at his management, or at his own decision to re-sign with the company that he suspects of undervaluing him.We could also look at his claim that the UFC's selective matchmaking favors the stars they want to build up, like Josh Koscheck , who Diaz suggested had benefited from especially easy fights early in his career."I never had fights like that," said Diaz.That's the kind of statement that feels true when you think about Diaz's early scraps against Chris Lytle, Robbie Lawler, and Karo Parisyan, but then you stop and remember that as recently as a few years ago he was beating up on the likes of Thomas Denny and Muhsin Corbbrey. Not exactly the best of the best.The point is, Diaz is entertaining not because he's telling it like it actually, truly is (there are certainly huge holes in his arguments) or because he's trying to put on a show for fame or attention (if anything, he seems like he'd rather be left alone...forever). He'd at least have us believe, or maybe have himself believe, that if he could make the same living in triathlons that he does in MMA, he might never strap on the gloves again.But as outspoken and unbelievable as he can be at times, Diaz is uncommonly genuine. He's honest, in his way, to the point of self-destruction at times.Dana White says he'd love to have him in the UFC if he would only "play the game" just a little bit, but that's the whole point: Diaz doesn't seem to realize that there is a game. If he does, he has nothing but disdain for it.To refrain from starting a post-fight brawl in a situation that he thinks requires it – whether it be in front of a live audience on CBS or in front of terrified nurses in a hospital hallway – would be some kind of personal failure to him. It would be insincere, and of all the things Diaz might be, insincere definitely doesn't seem to be one of them.At times that makes him a headache – if not a minor heart attack – for his employers. And whether he realizes it or not, his behavior has probably cost him a small fortune in missed opportunities over the years. But that only makes his absolute devotion to his lifestyle and his refusal to accommodate others all the more bizarrely impressive.Honestly, as much as many of us claim that we do whatever we want, or say whatever we feel, we usually don't. If we did, and we found that it was costing us a lot of money that we might otherwise easily have, we'd probably knock it off in a hurry.In that way, Diaz is living a more authentic life than we are. He is truer to himself, even if that means doing or saying things that range from confusing to downright criminal. He lives honestly, even if it's with a total disregard for decorum or civility much of the time, and he seems content to accept the consequences when necessary.On top of all that, he's also an amazing fighter to watch. Even Jason "Mayhem" Miller , who dislikes Diaz the person about as much as anyone on the planet, respects Diaz the fighter. It's the whole reason he kept trying to set up a fight with him, Miller said, because he knew Diaz "would really come forward and fight me."When even your enemies have to admit that you're very, very good at what you do, then at least you know you're doing something right.Which is why it's sad to hear Diaz express his frustrations with the sport and the pay. It's sad to hear him say he wouldn't do it if he didn't have to (though, admittedly, it's hard to believe).It's also, in a way, sad to see him methodically knocking off challengers one-by-one in Strikeforce, if only because it reminds us that some day, inevitably, Diaz will up and retire on us. And then what are we supposed to do for quality, authentic entertainment?