Now, I don't know Kris, but I can say this with conviction - Kris never wanted to be an actor at the beginning. If he wanted to be an actor right from the start, he would have never been a trainee under SM entertainment. It doesn't make sense for someone to want to be an actor to go into a country with a foreign language he is unfamiliar with and try to be actor there under a company famous for their bad acting. (Anyway, if you are not Korean, you don't get to be a famous actor in Korea). If he sincerely wanted to be a good actor, he would have auditioned at Hong Kong right from the start and tried to get into TVB or something. 

Kris just wanted to be a famous celebrity and being a Kpop idol was a way of getting famous. I have no doubt that he was dedicated to his dream - he didn't waste 4 years of his life training for nothing.