Agreed. With some managers it doesn't matter what you say, how well thought out your argument is to explain that they are wrong they just won't listen. They immediately close ranks, and switch into boss mode, "I don't wanna hear it, I'm the boss, I've made my decision, just make it happen!". The only way forward is to appear to agree with them, but to gently guide them in the right direction so in the end they think the decision to change was theirs not yours.