Yes, of course you can eat fondant. You just would rather not.

Being a paste of sugar or confectioner's sugar, fondant has nothing to commend itself to your taste buds. It's not horrible; it's just not something you'd choose to eat.

Most cake decorators know that if you're going to use fondant to decorate a cake, it had better be a pretty spectacular tasting cake. That's one reason so many fancy cakes have layers of raspberry cream or lemon filling, or are soaked with orange juice or some expensive liqueur. In Britain, they often cover a cake with a layer of marzipan before covering it with the fondant to compensate for the (lack of) flavor.