I've never come across "madness" in reading about the grandmasters. Crabby jerks? Yes. But it would be interesting to read about which chess players are deemed "mad".
Quotes on madness and chess

I don't believe in madness. I think it's just a label people have for those that are very different from typical society.
Madness is very real. I spent a month in psychiatric hospital against my will. I and many of those about me were definitely mad.
The fact is that clinical conditions are negatively correlated with chess performance!
Perhaps when quoting madness,chess experts have in mind just general conditions...
Thx
Chessplayers are madmen of a certain quality,the way the artist is supposed to be,but isn't in general.''
Marchel Duschamps
''The majority of competitive chessplayers are pretty level-minded,although there is a 15 to 25% percent among them who are mentally instable.''
Anonymous grandmaster in Guardian
''No grandmaster is normal.They only differ to in the extent of their madness.''
GM Korchnoi
Greetings