Hey there, Anon. That’s really awesome of you to say. Thank you!
You raise a lot of interesting questions in regard to Dean’s state of mind post-demonic experience. I suppose my perspective on the entire situation is that Dean’s journey, from death to demon to hero, is about discovering who he is. This is the first opportunity that Dean has ever gotten in his life for a clean slate - a second chance that isn’t preordained by God or angels.
Demon!Dean has convinced himself that he’s living the dream life that Dean wished he could’ve had in his absolute lowest moments - getting cheap thrills from bar fights, a different chick in his bed every night, a 90% subsistence level on alcohol. Demon!Dean believes that is his perfect life because he doesn’t give a fuck. That’s the life that Dean wanted when he just wished he couldn’t give a fuck about anything anymore, least of all about himself.
When Dean either learns to live with the demon inside or is cured of it, I don’t believe that his journey is going to be about feeling regret for all the things that he did. If he comes out of this wrought with the guilt for his transgressions, his agony for the people he has hurt - he’ll just be back to where he’s always been - a lost, broken man holding on the threads of existence. Dean’s entire life was his suffering before this. And he just can’t go back to that. In order for Dean to truly learn to be a hero, for him to save himself for once, he’s going to have to learn to let go - to let go of his past, to let go of what he’s done, and to let go of his brother. That’s the only way he moves on.