When we say someone has an "inflated" sense of himself, we're really saying that he's inaccurate.

In other words, he sees himself as having virtues that he does not have; or, he sees himself as having more virtues than he actually possesses. In a word: He's mistaken. It doesn't make sense, therefore, to say that such a person has "too much" self-esteem. It makes sense to say he's delusional, or mistaken. Don't blame too much of a good thing on the absence or distortion of that good thing. Think of it this way. Too much self-esteem didn't sink the Titanic. Erroneous judgment did. Departure from the facts--not departure from humility--is what sinks ships, literally and metaphorically.