Most likely his own twisted interpretations of being exposed to old pop culture growing up where the "right people" dressed in finer clothing, growing up LDS where it's commonly felt that "good, upstanding, righteous" men wear suits typically by the time they're teenagers and definitely by 18 for their missions (not all the time of course, but definitely for church and religious functions, weddings, funerals, etc.), and hearing the old axiom "you have to dress for success". Mix that all up in the demented mind of a narcissistic, mentally ill hobgoblin who wants to "stand out" from other young men who don't "put in the effort" of looking nice and dressing sharp, and who wishes to appear to others as someone who is successful and upwardly mobile (especially to the fine young ladies), and you get a guy who wears the same cheap, grody suit everyday, even when it's inappropriate to wear one (the gym, working his janitor job scrubbing shitty toilets, etc.).