If you ask someone why they wear blue jeans and they reply “because they’re comfortable,” they are lying to you in a way that is so total and complete I suspect they are also lying to themselves. Denim is a tough, rugged material meant to withstand time and the elements. Literally any other fabric would feel better against your skin.
Generally, when people say that something they wear is “comfortable,” they mean it is psychologically comfortable, not physically comfortable. We wear blue jeans because everyone else wears blue jeans, and it’s our nature to want to be part of a group.
Blue jeans were actually an accidental discovery in the 18th century, when people in Nimes, France attempted to replicate a sturdy Italian fabric called serge. What they created was “serge de Nimes” or, as it’s been shortened to, “denim.”