why is everyone making such a big deal about vaping? is it really that bad?

It's like a running meme/stereotype that men who vape are douchebags/show-offs ...and Jiwon is a douchebag, and kind of a showoff so it fits. I think Mingwa knows this joke
Thing is he only vapes in his place but smokes cigarettes elsewhere so he only cares about his place not smelling like cigarette smoke.