Why do women wear the same bra more than once?

Of course I know you can wear a bra more than once if you've washed it. But I've never met another female who wears a different bra everyday. I never wear the same bra two days in a row. I treat my bra like I treat any other article of clothing. After I wear it for a day- It goes straight to the hamper. So why do all these females wear the same bra like 3 days in a row? No offense, But I find that disgusting. People have told me "well it's underneath your clothes so it doesn't get dirty." That argument is completely invalid since sweat just like the rest of your body so your bra is getting just as much or if not more sweat and body soil just like the rest of your cloths. And CLEAN people don't wear the same underwear for more than one day do they? And those are also underneath your clothes. So, I dismiss that reasoning all together. But just why do they do it? Am I the only one who doesn't do that?