Dumbledore's character is complicated, and vast in trying to analyse, though many fans and critics have attempted to on multiple occasions. Despite his poor representation in the films, Dumbledore is by and large always fighting for the greater good, with only goodwill towards his fellow wizards, even if at times he does seem to make strange decisions. We can forgive Dumbledore his poor treatment of his family, the death of his sister, and his casual curiosity into the power of dark magic as a teenager, because his intentions overall are true. However, Dumbledore crossed the line from being a stoic leader to a calculating manipulator in his old age, and this is where he becomes a character who messed up. He never gave his followers all of the information they needed to make a free choice. He gave them only enough to manoeuvre them into doing what he wanted them to do (this was especially true of his two most valuable assets: Harry Potter and Severus Snape). Would he have done it all differently if he could go back again? Or rather, would J K Rowling? We'll never know.
I love Stephen King and music festivals; I eat my toast upside down; I daydream about getting married probably a bit too much; and I wish every day for a pet sausage dog puppy (who never materialises – sob).