why Charlie kirk was targeted.

Charlie Kirk was to Trump what Joseph Goebbels was to Hitler.
Joseph Goebbels was Nazi politician and philologist, who was known for his skills in public speaking and his virulent hate speech.
He used propaganda to promote the party and its programme.

Assassinations of people linked to despot leaders is Common.
Darya Dugina She was a very powerful social media influencer and daughter of a Putin ally. She was killed by a car bomb which was supposedly meant for for father.

If you threaten someone's food, shelter or freedom enough times, at some point there will be consequences.
People like their basic needs left alone.