Why did Sparta fall?

"Sparta broke with a sharp snap because it could not bend. The Spartans failed to rebound after Leuctra because they could not find a way to deviate from entrenched habits of rigid hierarchy, state terrorism, and social conformity. Leuctra was Sparta's fate because those habits led the Spartans to surround themselves by enemies abroad, while simultaneously feeding the angry hunger of those restive internal subjects who would happily have eaten the few remaining Similars raw."

"revolutionary plot by a group of Inferiors, led by one Cinadon. The hatred of Cinadon and his fellows for the Spartan system was summed up in their expressed willingness to 'devour the Similars raw.' Like the boy and the fox, Spartan society was, almost literally, being consumed from the inside."

Josiah Ober and originally published in the Summer 1998 edition of MHQ. Journal of Military History.

Sparta fell because it could not maintain (replace) an adequate number of its warrior elite similars. They relied heavily on helots to make up the numbers and these helots went from slaves to free men mercenaries.

Sparta made too many enemies with all around them and had internal bickering with non elites.

Spartas enemies learnt their tactics and how to beat them over decades.

Militarily the tactic sending too few men makes victory impossible and death inevitable, even if its heroic.

Sparta did not have an adequate economic income,

ALL ANSWERS ARE SOMEWHAT TRUE AND AT THE SAME TIME FALSE>THE REASON WAS TIME AND CHANGE. Sparta did not fall when it was in it's peak,but long after,when there were only crumbles of earlier glory.So it has nothing to do with flexibility but simply TIME.