I had a friend who was fired from, or quit, every job he had for nearly a decade. He response was always the same, "the boss is a moron" or "the people there are idiots". We had a long conversation where I laid it out for him. The odds that after 10 years everyone he worked with was an idiot or a moron were pretty slim and the only thing every single one of the those people had in common was him.

Fortunately he took me seriously and had a lot of growth in a short period of time. He's been at his last job for 15 years and moved to the head of his department and gets a bit of a laugh now when he hears that people working for him think he's a moron.