Doctor Strange may have deeper reasons to dislike Tony Stark beyond his personality, and it may have had something to do with Kang. Both Avengers: Infinity War. There weren't many opportunities to see the two heroes interact in the Infinity Saga, but it was clear that their egos would have gotten in the way of a possible friendship even if they had more time to get to know each other.
Other MCU characters have their own reasons to hate Iron Man. For instance, Scarlet Witch and Quicksilver witnessed their parents die due to one of Stark's missiles, and Mysterio saw Iron Man use his biggest work just for self-therapy purposes. Doctor Strange didn't have any personal grudge against Tony Stark, but while his aversion towards him may have stemmed from his ego, it may also have come from something sinister Iron Man was able to do and didn't even know it.
Iron Man Has Some Worrying Kang Similarities
Like classic Avengers foe and future MCU villain Kang the Conqueror, Tony Stark is a huge threat to the Earth and possibly the universe due to his extraordinary intellect and uncontrollable ambition. They're both capable of creating technological devices and high-tech weapons beyond anybody's imagination, and their reckless ideas often blow up in their faces. Iron Man always brought chaos everywhere he went, but unlike Kang, he was mostly limited to his own timeline. Tony Stark's invention of time travel brought him one step closer to Kang, but he sacrificed himself before he could wreak havoc in other realities.
Before Doctor Strange personally met Iron Man in Avengers: Infinity War, Tony Stark had already angered Whiplash and Aldrich Killian, created Ultron and failed to protect Sokovia, divided the Avengers, and played a role in various catastrophes across the world. Since Doctor Strange was tasked with protecting reality, which he made really clear to Tony Stark as soon as he met him, Iron Man's similarities to the most influential individual in the multiverse may have raised some red flags. Of course, Doctor Strange first needed to know about Kang to develop this fear.
Why The MCU Is Better If Doctor Strange Knows About Kang
Thanos flew under Doctor Strange's radar despite the size of his intergalactic crusade, but Kang's close connection to the MCU's multiverse may secretly make him one of Strange's biggest worries. The Ancient One already knew about alternate timelines as early as 2012, so it's possible to assume that Wong and Doctor Strange are already acquainted with how time travel affects the multiverse. Similar to how Loki's invasion in The Avengers informed Iron Man about Thanos' presence, perhaps Doctor Strange's research has led him to Kang's multiversal footsteps. And if Doctor Strange learned about Kang, seeing the villain's traits reflected in Tony Stark could have made him extremely wary of Iron Man's constant missteps.
Doctor Strange's knowledge of Kang's existence could make Kang's rise to power more dramatic in the Multiverse Saga, as Doctor Strange could have suspected him all along but been too afraid to confirm it. He could have tried to predict when such a figure would show up, and he could have been misguided by powerful characters who threatened the world. So, when Kang the Conqueror finally breaks out of the Quantum Realm, Doctor Strange will know that the time has come and the multiverse is at stake.
