Why is tyranny not being prevented when when the executive is inherited?

Having just fought a long war against what they considered a tyrannical government, the men at the Constitutional Convention were keen to prevent the establishment of what they termed “a democratic tyranny.”

Explanation:

James Madison wrote that “the preservation of liberty requires that the three great departments of power should be separate and distinct.” Why? Because the “accumulation of all powers, legislative, executive, and judiciary, in the same hands, whether of one, a few, or many, and whether hereditary, self-appointed, or elective, may justly be pronounced the very definition of tyranny.”

the french gave their support to another tribe during he war.

idk lol i just wanna finish mines