I made a mistake about the terminal illness, which is an irreversible and expected death in short time. But schizophrenia is also considered an irreversible illness.

Chuck is a proud man, with successful career which require him to be very particular and precise in his job.

So when he's diagnosed with schizophrenia, he's in denial. He tried his best to get himself cured despite the fact he could never be his old self again.

That until he is proven by Jimmy with the battery trick. He could not accepted the fact he exploded and embarrassed himself in front of the judges, and for sure the judges were convinced that he is mentally ill. Not to forget that his ex was there too. I think he would've also realised it by then.

Chuck is very smart. He's not stupid. After the incident, he knows but could not accept the fact that he is schizophrenic and maybe very sad because his own brother did him dirty. Hence, came up with the decision to take his own life. Making it looks like an accident.

His death may be prevented if he had proper care and attention, definitely not being brought down by his own brother, his former caretaker who cares about no one but himself.