The thing about spiders, and other arthropods, and reptiles too, that they donāt have emotions. That means they act in a logical way, they only care about food, sex and heat and they only attack, or even move, when itās necessary for their survival. They canāt get mad, they canāt have irrational fear, if you keep your distance, they wonāt waste resources and go to you and attack you.
Tl;dr: spiders are logical and predictable, donāt sit on them if you donāt want your ass bitten.