Doctor Strange has been a loose cannon in the Marvel Cinematic Universe since he became a player in 2016. He hasn't learned much from his mistakes over the years, and always causes some sort of damage to others when he uses his magic. After receiving only a few years of training from the Ancient One, Strange seems to have yet to master the art of dealing responsibly with superhero business.
After the events of Spider-Man: No Way Home, The Scarlet Witch publicly called him out on this truth. Strange's conflict with Wanda has pushed his irresponsibility to a boiling point that has eluded him for years.
Strange's arrogance was his biggest flaw and most defining personality trait in this debut film, and it rendered him nearly untrainable. Because of his excessive self, Kamar-Taj had to go to extremes in order to persuade Strange to listen.
Doctor Strange provided off-limits books, used the Time Stone, although it was forbidden, assumed he knew better than the people he was requesting to fix him, and made an enemy out of Mordo due to his chaotic, disrespectful actions.
The Infinity Saga
Several years had passed since Doctor Strange entered the big screen, naturally leading viewers to assume that he had matured over the years, off-screen. Strange did not develop much character development, though, and many fans implied that Strange intended to kill Tony Stark on purpose given how many future possibilities he considered in drafting a game plan.
Strange claimed to have seen over 14 million possibilities, yet there was one sequence of events that would culminate in the Avengers defeating Thanos. Fans were unconcerned about this, and felt that Strange was intentionally ridding the world of Tony, due to how dangerously arrogant he may be.
Spider-Man: No Way Home
Before the film was released, Strange's questionable decisions in the Infinity Saga were heavily based on speculation. His impact on Spider-Man: No Way Home was unquestionable.
Given all of the difficulties theyve faced together, Strange's desire to assist Peter Parker makes sense. However, Strange admitted to using magic for personal gain in the past to erase memories from people's minds after events that became out of hand.
Peter kept changing it mid-cast because he was too unprepared to explain the spell he was planning to use. He was also in a state of panic when he learned the truth.
Strange would have had the time to explain things to Peter before delve into the magic, and the web-slinging teen would not have had to make so many changes before it was too late. The biggest issue with this is that Strange blamed Peter for the whole situation and refused to take responsibility for his lack of communication, even though Strange was the one omitting information from a child in need.
Doctor Strange in the Multiverse of Madness
Strange was once again reckless with his magic use near the end of Multiverse of Madness. He used the Darkhold and was corrupted, as Wanda was, and his time on Earth-838 caused an incursion, as shown by the film's post-credits sequences. Yet somehow, unlike Doctor Strange 2 and his previous record, Strange remains a hero.
When Wanda Maximoff confronted her for the first time since the Westview incident, she says that when she breaks the rules she's demonized, but when Strange does it, he's honored as a savior. Wanda always takes responsibility for her actions, even if it takes a while for her to get there.
Strange is consistently arrogant and unreliable, and never takes responsibility for his mistakes fully. Whenever Strange gets involved, people are hurt or suffer severe consequences. The Post-credit scenes in the Multiverse of Madness appear to be directing Strange down a dark path that will hopefully encourage him to change his ways, or at least learn to be humble.