“The reason the Kennedy assassination is surrounded with conspiracy theories is because there is no doubt that the Secret Service was covering up SOMETHING.”
Respectfully I disagree, to me, what fuels speculation the most is that the accused assassin is shot down in police custody. Even today, that part is the most difficult part to grasp, on national TV and Ruby himself is a shady individual.
He wanted to be the center of attention so badly he couldn't stand it. After the assassination he was right where he wanted to be. You can see it in his smirk.
In his mind, he was finally getting the respect he deserved.