Everything, everything Tony has done has been done under the glaring flash of the press. From birth on, he can’t breathe in without it being public. He lived his teen years under public scrutiny. Every drunken mishap that most of us get to laugh off or slide under the mat was scrutinized. He had to love in public, mourn his parents in public, hide his pain and fears in public. To maintain the integrity of his company, he had to hold up his father image, the man who ignored and abused both him and his mother, as a paragon of industry in public. He had to bleed in public.
He gets no quarter from the journalists constantly tailing him looking for the money shot of Tony Stark doing something, anything wrong. This is why Tony hides his vulnerability. This is why he presents the arrogant and devil may care attitude to the world. Because the world is always, always watching him, ready to tear him down to the bone and leave him there until they need him again and there are only so many times a man can rebuild his soul.
The first armor Tony built wasn’t the Mark 1 in the cave. It was the one he wove from hurt feelings, choked back tears and his wounded and torn psyche courtesy of the press.