I think the issue and it's for all of us our trauma response is as individual as our face.
William has always appeared to be a bit more "stable" "cautious" in his actions.
William did well in education and went on to study at university. He was pretty much left alone best he could be to do uni. He met Kate here, he was friends with her first, and then they began a romantic relationship. Caution and patience.
He then joined the armed forces, was stationed at Anglesey with Kate, where again he was pretty much left to his own devices to cautiously mature.
It wasn't really till their engagement and then their young family was he thrust into the spotlight he is in now.
But by which time he was nearing his 30's.
He was heavily protected, and this is where I agree with Harry.
Harry didn't have that luxury, he didn't get that decade of break, he was always party boy, tabloid fodder whilst he attempted to mature into a young man. He was a bit of a grenade in the services, his racial slurs and then his inability to promote left him once again "without purpose".
Clearly still heavily traumatised by his mother's tragic death, without the ability to cope or will to try and engage with therapy properly.
It must have been enviable to see your brother, cautiously settled and well protected. But meanwhile pictures of you fighting paparazzi or attending the same parties as your brother were published in questionable outfits but none of William equally questionably dressed.
Envy, jealousy, trauma, spotlight attention, lack of consistency and belonging.
Recipe for disaster.
So yes they "share" a mutual trauma, but their life paths diverge massively after said traumatic event.
It's really sad.