This is because Bitcoin’s native monetary policy is elegantly simple, and its immutable supply is free from human discretion, something no other money has had since gold. In contrast to the yellow precious metal though, Bitcoin's monetary policy is algorithmically determined and thus perfectly predictable, rule-based. It is neither event- nor emotion-driven.
By depoliticizing monetary policy and grounding it in a code that follows a strict formula, Bitcoin’s monetary asset is structured as neutrally as possible. Bitcoin is truly sound money since it provides the highest degree of stability, reliability and security as a monetary system.