Daniel could have befriended the Cobra Kai
The first time Daniel entered the Dojo Johnny smiled at him as if to say, "please, join us and we'll teach you the way of the fist."
Rather than accept Johnny's warm welcoming smile, he smirked at Johnny and left without addressing anyone. So disrespectful. I think if he had joined, he would have been accepted by Sensei Kreese and after an initiation period he would have become one of the guys.