From the ancient days, kings were military leaders. Israel disrespected YHVH when they asked for a king because YHVH went before them and fought for them. Granted, they were allowed to have a king so Yeshua could become the ultimate King, but you get my drift.
The tradition of kings being military leaders carries through to today except in western democracies. Our nation was prepared to make George Washington king after the defeat of British Empire. Washington refused and instead, we got a form of government where the military power resides in an office that changes hands. We in the US do not serve an earthy king. We support our constitution and the office of president, understanding that men are flawed. I will not serve an earthly king, nor will my children. Our King is Yeshua, who's power and authority were given to Him by Yahweh, Creator of the Universe.
In #deuteronomy 17:14, God told Israel that they could have a king if they wanted. Contrast this with Samuel's disgust when Israel demanded that he give them a king a few hundred years later. The problem wasn't that they wanted a king, but their reasons for wanting one. They didn't trust God. They feared the kings and armies of their neighbors and thought they needed their own to be secure.
It's not a sin to want a king. In fact, we're supposed to want a king, but the king we should want is #yeshua (aka #jesus), not Saul, and not even David.