Why assume that zero exists?

(I'm not talking about an identity element in a mathematical sense, because there the existence of an identity element is, if it exists, derived from axioms) The existence of zero requires a proof, which is impossible in my opinion Schopenhauer discussed about pain / suffering and happiness, and that pain is direct and happiness is indirect It kind of assumes, not necessarily though, the existence of zero And almost all people's morality also assumes the existence of zero That assumption is so absurd Actually, this so-called zero is just an arbitrarily determined point in an ordered infinite set, nothing absolute