Well yeah, that's the Münchhausen Trilemma. When looking for a final reason, if you don't want to make an axiomatic argument like "because God", you must end up either going in circles or down an infinitely deep rabbit hole. Since none of these options are satisfactory, the search for a final reason is doomed from the start (though it can still be fruitful).
"How we ought to live."
I think that's a bit circular, Socrates.