Is There a Moral Duty on Me if No One Exists?

I think then maybe we tabble ethics just I think there's a lot of utilitarian who would say that is ethics. If you're the only person in the world and have a moral duty to make yourself as happy as possible  who is imposing that duty on me if no one else exists? "There may be other other formulations of ethics out there but I am unconvinced that they aren't wrong so but it does"