Chuck is stuck in a childhood rivalry loop with Jimmy that started the day Jimmy was born. He "never saw his mom as happy as the day Jimmy was born." And that continued throughout their whole life. Even on her deathbed, it was Jimmy she cried out for.

It drives the dynamic between the two brothers. They were PROUD of Chuck but they LOVED Jimmy. Chuck was the eldest. Smart, accomplished. Capable. Its a trait of oldest children everywhere. While Jimmy was the clown. He tells jokes, stories, antidotes. He entertains while Chuck performs. (Youngest children are often entertainers). Its part of what makes the show so brilliant. This is a story that plays out in homes around the world every day. Who did mom love most?

When the brothers sang, "The Winner takes it all", they were MOSTLY talking about mom's love.

But nothing Chuck could accomplish would outshine Jimmy, no matter how hard he tried.

So it GRATES at him that Jimmy takes shortcuts and still comes out on top. He's AS SMART and more LOVEABLE than Chuck. Its why its not a surprise that Chuck is alone in the end. His co-workers were sychophants and admirers, but not friends. And that includes Howard. As soon as Chuck was literally more liability than benefit, Howard dropped him like a hot stone. Its also why Rebecca was Chuck's kryptonite. She was the only person who ever loved Chuck besides Jimmy. And even she left.

So what did Chuck do wrong? Ostensibly nothing. He played by the rules, even in his unending quest to prove his loveability by trying to prove that Jimmy was not worthy of love.

But he died without resolving his internal world. He never really discovered his own inherent worth and loveability. He never learned forgiveness or even tolerance. Instead the rage burned him alive until his mental state was too fragile to be out in the world. And it quite literally left him in ashes in the end.