In 2008, the MCU was launched when Iron Man hit the theaters. No one could have possibly predicted the domino effect this film would have once Tony Stark said those four little words: I am Iron Man. Nor could they predict the journey that Tony Stark would take over the course of twenty-two films.
At first glance, Tony has remained the snarky, intelligent, suave billionaire/inventor as he started. However, it is easy to forget his less than humble beginnings as a vain, greedy, naive, playboy war profiteer. That all changed when he was taken captive by terrorists and escaped with the help of the selfless Ho Yinsen. Since then he learned from his mistakes and tried to become a better person. As a result, Tony Stark changed in ten ways between Iron Man and Avengers: Endgame.
Spoiler alert for the MCU!
10 Dropped His Hedonism
Before the world knew him as Iron Man, Tony Stark was just a party animal wasting his wealth on parties, booze, and women. Even after unveiling himself, Tony was still prone to throwing wild parties and suffered from functional alcoholism in Iron Man 2. That aspect was slowly weeded out as the stakes grew and Tony prioritized his efforts on protecting the people he cared about. He also stopped playing around with random women and stuck with one.
9 Learned To Appreciate Pepper
Pepper Potts was just another employee at Stark Enterprises to Tony when she was first introduced. Time and time again she proved her loyalty and devotion to Tony helping him face Obadiah Stane and Aldrich Killian.
It slowly dawned on him that she was too precious to lose as an assistant and a romantic partner. By Endgame he refused to help the team with their time heist because he couldn't abandon Pepper and their daughter again. At that point, he would give his life just to protect them like a good husband and father.
8 Discovered His Dad Did Care
Speaking of fathers, let's discuss Tony's relationship with his father Howard. The two never saw eye-to-eye growing up and didn't patch things up before Howard's death. It wasn't until Iron Man 2 that Tony found his father's recordings and learned how much he cared for his son. Tony belatedly realized that his father did love him in a distant way and in Endgame he heard it straight from his mouth. Finally realizing that the two of them weren't so different after all and that it wasn't a bad thing.
7 Cooperated With the Government
If there's one thing that Tony hated more than anything it was being told what to do. In Iron Man 2, he refused to relinquish his Iron Man technology to the government and in Avengers he hacked into S.H.I.E.L.D. because he wasn't comfortable blindly following their orders. He changed his tune in Captain America: Civil War when he sided with the U.N. on the Sokovia Accords and initially lets the authorities bust Vulture in Spider-Man: Homecoming. By that point, he realized that upsetting the government was not the smartest move and it was the only he could retain some control.
6 More Hands-On
Getting captured and learning who his company sold weapons to was a real eye-opener for Tony. It's no wonder that he started placing himself at the forefront of everything. The old Tony would have hired someone else to be Iron Man but instead he brought it upon himself to face his challenges head-on.
Most likely it's because Tony is so vain, he believes the world revolves around him meaning if something awful happens he blames himself. In his eyes, that means only he can resolve the issue.
5 Charitable
Everyone knows how Tony Stark contributes to the Avengers and assists in protecting the world but his altruism doesn't end there. He established the Stark Relief Foundation to help those caught in the crossfires of Avengers's battles. He also set up the September Foundation which provided funding and grants to school to help prodigies as shown in Civil War. Although Tony made some bad calls in his quest to protect the world he made some noble ones too. Truly proving that Tony Stark has a heart.
4 Actions Have Consequences
For someone as brilliant as Tony Stark, it took him a while to realize that his actions had consequences. Even after he realized what his company was doing he still acted impulsively to right his wrongs. Resulting in him making things worse like challenging the Mandarin or creating Ultron. It would explain why he was so willing to sign the Sokovia Accords and why he didn't use the Iron Man suit as much after Civil War. He realized that wealth and armored suits didn't give him the right to charge into danger.
3 Growing Paranoia
Although he survived the Battle of New York in Avengers, that didn't mean he escaped unscathed. Tony saw the forces Thanos had under his control and was the only Avenger to know of the threat that would return. To quote Tony in Infinity War, "Thanos has been inside [his] head for six years, since he sent an army to New York,". Scarlet Witch only made it worse in Age of Ultron when she showed Tony a horrific vision.
It's evident in his attempts to develop countermeasures like Ultron and that he was desperate to have a strategy for Thanos. Even if it meant taking drastic measures.
2 More Precautious
After coming so close to dying and losing those closest to him, Tony went above and beyond to protect them. Starting with him building the Rescue suit specifically for Pepper in Iron Man 3. He placed Scarlet Witch on house arrest to avoid drama. As enthusiastic as Iron Man was to bring Spider-Man on to the team, he wasn't willing to let Peter take on bigger crimes or join in Infinity War. The fact that he installed a parachute in the Iron Spider suit was likely added to make sure Peter didn't experience the same fate as Rhodey. The old Tony would never have cared that much about other people.
1 Learned To Trust Others
Who could blame Tony for being distrustful of others? After all, there are not many people as skilled as Tony Stark or capable of dealing with the problems he faced. As such, it explains why he was reluctant to rely on others when he is usually the smartest man in the room. Yet in Infinity War he went along with Star Lord's plan to subdue Thanos and in Endgame trusted Captain America to go back to the '70s to find the Tesseract. Even his final sacrifice could be seen as him placing his trust in every other hero to continue protecting the world in his absence. Either way, he no longer had to shoulder the burden of protecting or avenging the world.