Hyuuga's favorite drink is Coca-Cola, and he consumes it whenever he can despite knowing how it's not healthy. So why does he insist in drinking something that could potentially cause him health troubles when consumed in excess? That's because Hyuga was VERY poor as a kid so he couldn't afford to drink Coca-Cola regularly. (And one of his part-time jobs was carrying around empty bottles); now that he has a regular income and a good part of his goals are secured, he feels that he can allow himself that little pleasure. You can say it's a bit of Comfort Food effect.
In the WYC manga, there's Stefan Levin. He often plays very violently and has injured more than one rival, like Wakabayashi and Müller, and we even get to see him harming Akai via hitting him point-blank with his strongest shots. Okay that's harsh... but the fridge horror kicks in when we recall that Levin has such Super Strength... that he's able to destroy a statue with a single shot. Suddenly his super aggressive and cold playign style takes a much darker turn... It's almost a miracle that Akai is even still alive.
Again in the WYC manga... why is Hyuuga so horrified when his mother falls ill, to the point of having a massive Heroic BSOD? It's not just because of Mrs. Hyuga's brush with death, but because said illness was an almost fatal case of karoshi... aka the infamous death from overwork. Which almost overlapped with Death by Falling Over, as she hit her head and got a concussion when she passed out. Remember, Hyuga's mother was widowed with several little children and she always insisted that Hyuga should NOT take part-time jobs so he could focus on his studies... so now that he cannot directly help her with physical work due to having his own job and training, she doesn't have his help and/or his reminders of how she shouldn't overwork herself — and ended up collapsing. One can imagine the horrifying guilt that Hyuuga must have felt upon being told what was going on, specially considering his early story: not only he was this close to lose his remaining parent (flashback to his dad's death included), but her being in such a bad state coud have been avoided if he had been there to remind her when to stop, since Mrs. Hyuuga didn't listen to her workmates when they tried to warn her. And for worse, he can't go back home due to the current conflicts... W H O A. Powerful woobie vibes there.