[brc]

It's usually the way someone was brought up.

Lots of parents spend their days blaming other people for their lot in life, and taking no responsibility themselves. They do this loudly to each other while the kids are there.

Little kids have big ears and learn by imitating.

Once the pattern is set, it's like kiln-fired concrete. When that kid makes it into management - everything good that happens is their doing, everything bad is somebody else's fault. It's unlikely that person will ever change unless they have some sort of epiphany.

Personally I hold myself responsible for all outcomes assigned to me. In the cases where it could be plausibly not be my fault, I still allocate blame for not having foresight to avoid the situation. This is my hack to prevent development of a blame reflex, and to enforce learning from every poor outcome.