3x16 Dan

Was Dan's choice to shoot Keith fueled by the genuine belief that Keith was the one who shot the dealership on fire?

I guess I just don't understand why Dan hates Keith with a burning passion. Is he just a psychopath or are actual transgressions Keith has made? Yeah he slept with Deb but Dan didn't give the first F about Deb to begin with. And wasn't hiring Jules enough payback? Like tf.

The childhood flashbacks only demonstrate Keith being a good brother from the start.