There is a fine line between having a healthy ego and having an inflated ego: you know it, but someone you'll be dealing with today does not! If you are feeling charitable, you can save them from themselves by stepping in and preventing them from saying something they will regret later on. But if you're not feeling especially compassionate, feel free to let them dig their own grave. But be careful: their demise does not necessarily mean that you will be stepping into their shoes.