Most people need at least two suits to cover interviews, weddings, semi-formal events, parties, and funerals. Office workers may need at least double that number, to put into rotation. Budget plays a large factor, of course, but the reality is that for some professions and workplaces, a suit is the expected uniform.
Because an ill-fitting suit sends the wrong message, it’s worth it to survive on ramen noodles for a while in order to get a really nice, well-fitting suit.