No, bettas don’t eat moss balls. Betta fish are carnivorous, so they will generally not eat moss balls or other plants.
With that said, moss balls are wonderful tank buddies for your bettas. Your betta can play with them, and because moss balls are fluffy and comfortable, bettas love resting on them. Plus, moss balls can also help produce oxygen, remove waste, reduce algae, and encourage the growth of beneficial bacterias in your betta’s tank.