I love how in the first Avengers, Steve basically asks Tony what would he be without ‘suit’. Tony’s response is, of course, “Genius, Billionaire, Playboy, Philanthropist.”
Essentially, under the armor, he had more armor. Things to hide behind long before he was ever trapped in a cave with a box of scraps. He hid behind his intellect, his money, his intimacy issues, and his need to be useful to hide that broken little boy from the big bad world.