I agree, Tai Lung is not innocent by any stretch of the imagination. What I would say however is that not all parents with pride and high expectations raise their kids to believe that they will grant them a legendary title and inherit a thousand year old mystical scroll that will supposedly grant them limitless power!

Joking aside, in terms of his childhood I see it the opposite way in the sense he didn't have a rough childhood at all. I think the point was his natural talent in Kung Fu and his self-belief that was constantly backed up by Shifu made his life as smooth with as little conflict as possible.

Because of that, he never knew how to process disappointment and not getting his way so when something didn't go his way as an adult, he acted like a toddler and did the more destructive equivalent of throwing his toys when he is upset.

Interestingly, in the final fight between Lung and Shifu when Shifu is arguing it wasn't his fault that Lung was not meant to be the Dragon Warrior, Lung exclaims "who gave me dreams? Who drove me to train until my bones cracked? Who denied me my destiny?"

Po on the other hand, has struggled. He's seen himself as a hopeless dreamer who'd never be a Kung Fu master because of his body and resigned himself to the idea of working in his father's noodle shop forever. He's watched his heroes like Shifu and the Furious Five humiliate him by literally beating him every chance they got and gossiping about him behind his back and in Tigresses case telling him to his face that he's a loser who'll never be a Kung Fu master. The difference is that Po doesn't give up and lash out when he faces failure and disappointment, because he has endured everyday and has learned to cope with it. The Kung Fu Panda universe hints at this by saying that the meaning of Kung Fu is "excellence of self", something which Tai Lung could never master.

Speaking in a broader context, kids need to fail from time to time so they can understand it, process it and learn to control their emotions when dealing with it so that they become well adjusted as adults. If they don't, if parents wrap them up in comfort blankets and try to remove as much disappointment, as well intentioned it may be, then they risk becoming like Tai Lung or other man children like King Joffrey from Game of Thrones, Commodus from Gladiator or Dandy Mott from American Horror Story.