Failure is part of the learning process. When you fail at something it's an opportunity to look back at your mistakes and improve yourself going forward.
But that's the thing... it's just an opportunity. If you fail at something, shrug your shoulders and say, "I guess I'm just a failure." then not only are you not growing as a person, you're nurturing negative habits that will actively inhibit your success in the future.
Celebrating failure is fine. Failure can help you realize that you aren't cut out for something. Maybe chasing a degree in one of the hard sciences is too taxing for your mental fortitude. Maybe the career you're pursuing doesn't gel with you're personality and you're making yourself miserable by soldiering through it. Maybe you've rushed into a relationship in your early-twenties and now you're engaged to someone who you don't love because you felt left behind by your married peers. Maybe a failed business venture put your brand in the hot-seat for an underdog comeback story. Whatever the case may be, sometimes failure can play such an overwhelmingly positive role in a person's life that it dramatically increases their quality of life once a change has been acted upon.
But that isn't what this movie is about. Its message is, "Yes, the world is wrong and you are right. You do you, girl! Now double down and go make a scene in public."
Tl;dr This movie is sending its target audience, who I can only assume are 16-20yo college students, the wrong message about life by only reiterating what they want to hear.