Every Marvel fan knows that there are a few plotholes in the MCU, but as a fan, little inconsistencies are easy to ignore. One thing that impossible to ignore is the fact that Iron Man can be a jerk. Over the course of a decade, Tony Stark has managed to fuel the MCU's black market weapons trade, he’s inspired a cavalcade of evil copycats to build their own robot suits, and he’s ultimately responsible for Earth being attacked multiple times.
Tony Stark is the catalyst for most of the problems faced by the Avengers. By putting his face out in the open as the identity behind Iron Man, he put a bullseye on Earth. No wonder aliens keep trying to destroy the planet.
After seeing a vision of a horrible future where all the Avengers are dead and the Earth is wrecked because Tony didn't "do more," he decides to create the Ultron global defense program to protect the planet. While his intentions were good, his execution was sloppy at best. Tony and Bruce pluck a yellow stone from Loki's scepter and, without ever really studying it, just plug the gem into an artificial intelligence tasked with the mission of protecting Earth.
Tony doesn't even think to use Asimov's Laws of Robotics as a safety net, and of course the AI quickly decides that the best way to protect Earth is to destroy the human race. If Tony had taken a little bit more time thinking things through, the Avengers wouldn't have had to stop a robot from trying to turn a sovereign nation into a comet capable of wiping out all life.
Tony plays the role of a hero, but he has all of the classic characteristics of a villain. Chief among those characteristics is his pettiness. He's unable to drop any slight, small or large. His pettiness creates villains like Hammer and Killian, and it also ruins his relationship with Steve in Civil War. Even though Tony knows Bucky was brainwashed when he killed his parents and that Zemo showed them the video of their deaths as a ploy to get the heroes to fight, Tony can't control himself. He goes right along with Zemo's plan and faces off with Bucky and Steve in a no-holds-barred slugfest that does potentially irreparable damage to their relationship.
Feeling guilty about his own complicity in previous world-threatening events, Tony puts his full support behind the Sokovia Accords and the plan to give the UN oversight over the Avengers. When Tony forces the Avengers to sign the Accords, he creates a rift in the team that is exploited not only by Helmut Zemo, but also by Thanos in his quest to gather the Infinity Stones. By forcing the issue of the Accords, Tony actively drives a wedge between Earth's greatest heroes, making sure that there's no centralized group of first responders ready when the Black Order attacks.
Villains inadvertently created by heroes are a common trope, but Tony creates enemies because he is imminently punchable. Regardless of whether he's embarrassing Justin Hammer or bullying Aldrich Killian, his attitude is off-putting and adds a touch of venom to every situation. He's so smug about his work and station in life that it's natural to want to bring him down a peg. Since Tony's one of the most powerful people on the planet, his foes resort to drastic means in hopes of bringing him down.