I seriously don't understand.
This is Yukihara in chapter 4,
Look at this little shitface. Initially, it was a character point that Yukihara's cooking was developed through practical training in a kitchen, which contrasted the "coddled rich kids" stereotype they applied to the rest of the academy. However, that lasted for all of 10 chapters because they quickly introduced a whole cast of characters who worked as hard as he did and had as much reason to be there as him.
Where the hell were the complaints about him being arrogant? Do I need to go through the entire manga and pick out every panel where he challenges someone to a match with a smug look on his face, and comes out ahead? Is it, like, because he's the hero he can get away with being a tit? He has all of Naruto's hubris but with Sasuke's talent backing it up so he becomes an insufferable juggernaut that's immune from criticism simply because no one is on his level.
If Hayama was the star of the manga, guess what? He would have the exact same reasons as Soma to be a cocky cunt.
Like Soma, he proved himself every day as a practical chef by aiding and implementing Jun's research.
Like Soma, he doesn't come from a background of privilege or wealth.
Like Soma, he's damn near invincible.
Like Soma, Hayama doesn't limit himself to one kind of cuisine (like people typecasted him as, it was obviously misdirection). His scientific upbringing makes him a good an innovator as Soma.
They are almost
exactly the same except for one aspect. Hayama cooks to validate both himself and Jun. Soma cooks solely for himself. That was the point chapters 103 and 104 tried to hammer into your head over and over again. If you want an analogy, this is the equivalent of a shounen battle manga where protecting your loved ones makes you stronger. By losing to Hayama, Soma realizes he has a new avenue of growth beyond simply "becoming better" as a chef.
This is actually ironic, because Hayama is presented as the lone wolf type
yet it's love for Jun that fuels his cooking. Soma is the gregarious dude who inspires and befriends everyone around him, but his cooking is completely self centered.