No. Nail polish is good for your nails, actually. Contrary to popular belief, nails don’t need to “breathe”—they’re like your hair, dead. Yes, nail polish will discolour your nails, but again, just like hair, just because your nails are coloured does not mean they’re not healthy. Regular, quality nail polish is not bad for your nails, no matter how much or often you wear it.
Nail polish is good for your nails, why? Firstly, it adds the extra layers that keeps your nails strong and less prone to breaks and chipping. I’ve been chipping my nails a lot since working in retail (using hands a lot) and working in food and beverages (getting my hands wet a lot). Ever since I started getting into nail polish, my nails have never been as long as they are now for a loooong time. It is perfect for anyone with thin, brittle nails.