I agree with @denmarkguy, which expressed the most plausible hypotheses.

The reason for the suicide is probably due to his success, which, ironically, caused him uneasiness that he had tried to reduce by using alcohol.

This, unfortunately, did nothing but worsen his state of health, causing him to fall into depression and leading him to the extreme decision to commit suicide.

Thanks for the bounty, @knircky... a big hug from @amico!