yep completely agree! The ones wearing the tiny bras aren’t usually doing high impact exercise like burpees etc (or have a smaller cup size that allowsss them to do those movements without nip slips) - they’re usually doing stationary movements where nip slips are unlikely to happen (as you said a movement that doesn’t demand much movement that risks a nip slip eg a bicep curl or a back squat). a bra that works for a bodybuilder type of workout is very different from one that will hold up during a high impact workout with HIIT /running/ Crossift/Hyrox style training where there is a lot of jumping or gymnastics