Sweat pants would make sense.
I am interested in the psychology concerning BK's fascination or obsession with the movie "American Psycho". I've never seen the movie so I got this from AI about the plot:
"The story centers on Patrick Bateman, a handsome, well-educated, and wealthy Wall Street executive who maintains a meticulous morning routine and a facade of normalcy while descending into violent, hedonistic fantasies and acts of murder at night." Another description of the plot said "misogynist attitudes"were on display too and maybe that's where BK first picked up his very odd horrid attitude toward women we have heard so much about going all the way back to his earlier years before Idaho.
I find the "meticulous morning routine" of the psycho in the movie interesting as well as the "facade of normalcy". I can easily picture BK adopting those for himself. And the "nightime fantasies and acts of murder at night" can certainly explain his middle of the night wakefullness. But on the "handsome, well educated, and wealthy", gag me.

Yet I'm thinking he may have really believed he had perfected that whole entire persona, accounting for his general overall overly inflated view of himself.
What are the odds he first saw American Psycho at a young "budding" or imprintable developmental age and was eroticized by the lead role in American Psycho? Maybe he began to cosplay the traits in his own real life from a very young age, and in a narcissistic twisted way eventually fell in love with his own self as that role? Maybe that explains his "self love" night time selfies? I'm curious also as to how he envisioned his life *after* his murders, given that he was tanking at Life 101 overall. Addictions cause many students to fail in school and maybe his was a compulsive murder fantasy addiction that caused him to be so very odd that it eventually got him kicked out of school or was it that he just lost his assistantship job? I'm not clear on that detail.
Any idea how a person would go about finding out how old BK was when he first saw American Psycho? The movie first came out in 2000.