Reply To: Why do Litvish and Modern men always have their top shirt button open?

They’re following David HaMelech. When his clothing got in the way, he did away with it. Only difference is he did it l’chvod Shamayim, for HaShem’s honor. Why these people do it? Maybe they’re trying to concentrate on a hard piece of rashba or k’tzos, they need all the ventilation they can get.