Sometimes it's about matching the fashion of the group you aspire to be part of, sometimes it's about having that fashion imposed on you so you look "professional".
Security guards at tech company offices are the only ones who wear suits, presumably because it's a mandated uniform, not by choice.
Apocryphal, but someone once told me history of male grooming is an example of this: When only rich people could afford to shave, the fashion among the noble was to have a clean-shaved face to signal status, and poor people had beards. Once safety razors appeared, then the trend reverted.
Security guards at tech company offices are the only ones who wear suits, presumably because it's a mandated uniform, not by choice.