If he’s such a prick, why do you consider him a friend?

I've known him since 2000. He wasn't a prick then; his personality had a complete makeover. And we're both interested in philosophy and spirituality, both

very analytical, and both have issues from an extremely traumatic childhood

i don't really make new friends so i don't want to get rid of any of the few I do have. and for some reason I like talking to him.

(when he's not being an a$$hole)

(and even though I have to be very selective about what I say)

I understand. I was simply curious. :)

Why do think his personality changed?

We had stopped communicating for a few years and when we started again he was different. When I said he turned into a dick (using whatever words I did), he said

he hadn't been in touch with himself before, or something like that.

it's understandable that he would be a prick since he's in so much physical and spiritual/emotional pain all the time

but that doesn't explain why he wasn't before