"I feel like the only one who thought MU was depressing. Mike wanted to be a scarer, studied so hard to beat ever obstacle thrown at him just to be told he wasn’t scary enough, that despite all if his hard work, he could never be one. He was so dedicated, but never made it. All my life I’ve wanted to be an imagineer at Disney and helping to design rides that would bring magic to everyone who rode it and now I think that maybe I won’t get that chance…If Mike couldn’t do it, what chance do I have?"
Oh OP. More or less the point of the film was the realistic fact that: No, your dreams won’t always come true- and to be honest it’s insulting and boring for every movie again and again to say teach this (untrue) lesson. There’s people out there today who tried their hardest but didn’t make it and people even try and say they didn’t want it enough or tried hard enough which is utterly wrong.
Failure happens. But it doesn’t mean you’re a failure as a person if it does.
However: if you try your hardest you still might end up somewhere great in the end even if it wasn’t what you originally planned. And Mike did.
He got a best friend for life, he was the trainer of a top scarer- someone he personally trained who was damn close to the Scare Record in Monsters Inc and they were a great team and Sulley was well aware he couldn’t have made it without him. He also had helped monsters who the administration had given up on to become Scarers too. And later on in life he got a great girlfriend and even became an Amuser/Comedian- ending up on the side of the door he had wanted to be on- just in a way he didn’t think of all those years ago. Life is funny like that. But even if he hadn’t become a Comedian he was still clearly happy before that.
Heck I’ve said this before but Mike in Monsters University is also kind of a play on the old saying ‘Those who can’t- teach’ (usually to insult teachers) with the answer: ‘So what? Teachers are still important too and it’s a skill set all on its own’.
Heck there are people who are fantastic at something yet couldn’t teach their way out of a paper bag- if they’ve never struggled with it or had to look at something from a variety of angles they might not really ‘get’ where a student or different students are coming from. Just because you’re a maths wizz from a very young age and could be a complex physicist of some description does not mean you have any hope of being a good maths teacher.
The thing is: Mike didn’t become a Scarer, but he still was happy as an adult both before the big events of Monsters Inc and afterwards.
Mike is someone who can’t Scare. But he is someone who can teach it.
Just because you find you don’t achieve your original dream doesn’t mean you can’t find a new dream or purpose. Nor does it mean that you have no skills- they just might be in areas you didn’t think of.
It doesn’t mean that you can’t eventually be happy.
And I think that’s a great lesson to have.