You can think about the details like that when you have everything else on point, plus Kyrie was a good enough playmaker in Cleveland when he played second fiddle to Lebron but he thought he was getting overshadowed by Lebron and thought he could lead a team himself. Don´t forget, he claimed 2 years ago they don´t need a head coach and that he or KD could be the coach and switch with Nash whenever it is required
And KD has the same issue, he thought he was the main guy in GS, and thought he had to get away to prove that, and here we are.
Both suffer from overgrown egos for different reasons (KD with his insecurities, Kyrie on his "i know everything better" ego trip).