He said it was all he knew. It was the only way he knew how to be. Honestly, I believe him.
"All I knew" from the life I was handed was this: Life was meant to be spent drinking as much as you could, b****ing about everything that didn't go your way, never taking responsibility for anything, hating anyone who was different (color, religion, class), never having enough money, always needing more "stuff," and you just struggle through it, and then you die.
We take what we're handed and make something better out of it. There are a thousand thousand models out there of different lives we could have, if we just decide we want something different and stop making excuses. "It's all I knew" is the biggest load of BS there is, imho.