Look nice (if you’re into that look, which many people are)
Keep your nipples from chafing
Support/containment for larger boobs
Keep prudish people from being mad at your nipples
Can be worn without a shirt for sports if they cover enough real estate
When breastfeeding, help catch/absorb leaks
Disadvantages of bras:
Uncomfortable if not fitted right
Sweaty as fuck on hot days
Expensive
Many have to be hand washed if they are fancy
I would say I wear bras about 30-50% of the time and it’s usually for either support/chafing prevention or looks. The rest of the time I can’t be bothered. I’m also lucky to not have super large breasts. I know women who do may find a good fitted bra to be more comfortable than no bra.
When I was breastfeeding I wore them all the time though because it is super awkward to leak through your shirt in public.
Edited to add bullet points bc I suck at lemmy formatting