Tyler Durden is not bound by convention. He does not play by the generally accepted rules of demeanor, modern capitalism, or clothing.
Getting recreationally punched in the face is attractive to very few people, until they see someone who looks unusually attractive getting his tooth cracked. Then suddenly people want to be that guy.
Were this guy wearing a standard business suit he would appear an authority figure and hence a bully if in fisticuffs.
If he were just wearing a t-shirt and jeans he would likely be dismissed as trailer trash whilst scuffling.
There are those who would point out that Fight Club is just a movie and Tyler Durden isn’t a real person.
When it comes to fashion, Durden is every bit as real as Brad Pitt.