Many people - newspapers and journalists - all people who didn't know him, thought him to be vain and egotistical. And they were right, he was, to a certain extent. But what these people didn't know, and nor would they ever if he had anything to say or do about it, is that there was a difference to the person he pretended to be and the person he really was.
Perfect example: when he went out, he wasn't afraid to flaunt around, and yes, it might've seemed like it was a bad idea at the time - and it often proved to be a bad idea if he looks back to his time at MIT - but the thing was that he knew he was a catch. He had two out of the three 'tall, dark and handsome', and honestly, just the fact that he was richer than God should be enough to make him the perfect all-rounder.
His theory was proven time and time again when men and women alike three themselves at his feet, unaware that it was all just a front, he wasn't into all of that and he mainly did it because it was what was expected of him. People expected him to strut, to smirk and wink, to throw money around like it was nothing. They expected him to be a playboy, nevermind the fact that he only slept with a handful of people, and the rest that he took home were too drunk to do anything, so he put them to bed. Consent was sexy, and sex with consent was everything to him, he made sure that his partners were treated right and felt good and in return, he hoped to feel good, too.
The people who woke up embarrassed and hungover the next day were the ones who did more harm than good; telling someone or more than one person that they slept with Tony Stark and so rumors spread, the tale gaining extra embellishments and so a reputation was born.
What the public didn't see was how much he hated himself, his body, his reputation. He could barely stand to look at himself in the mirror on bad days. On days where he was feeling particularly disgusted with himself and his appearance, he would stare at the scars on his chest in disdain, uneven bumps and raised scar tissue littering the expanse of his chest. In between the scars from the reactor were thin silvery lines that trailed along his chest, silvery lines that were left over from the time when he was being poisoned by palladium from the reactor, scars that would never fade.
And while he hated himself and his body and the scars that littered his body, Steve loved him, never stopped showing him just how much he did, worshipping his body until he was forced to believe that maybe someone could love him and his old, broken body.
He still hates his scars, and whenever he sees or hears something like 'your scars make you beautiful' or 'the scars that remain shows just how brave and strong you are' he can't help but scoff. It's stupid and untrue, and people should stop giving opinions on things they didn't know.
But on the bad days, when he can't look at himself in the mirror, can barely bring himself to look at his chest, much less touch the area near it, Steve will come by as if he knows exactly what is going through his mind and lay a gentle hand over the place where the arc reactor used to be, and sometimes, when they were alone and in the comfort of their bed in the penthouse, Steve will trace a feather-light finger along his scars and lay a kiss on his chest. He never said anything, but then again, his eyes always told a story of their own, shining with love and something else he couldn't quite place.