Why did Spartan society fail?

Could you elaborate on the reasons behind the downfall of the Spartan society? Were there specific factors, such as economic decline, political instability, or social unrest, that contributed to its demise? Additionally, how did the society's unique military and social structures play a role in its eventual failure? Understanding these factors may provide valuable insights into the complexities of ancient civilizations and their resilience or vulnerability in the face of change.