This maxim is more than just an admonition to despise insolence; it is one to despise hubris in all its many forms. Hubris is the virtue of pride taken to extremes. It is one example of what happens when we forget the Maxim which tells us “Nothing to extremes” and is one of the most destructive forces in the human condition.
This does not say that we should denigrate people for being proud about their achievements as they have put the effort into doing what they are proud of. If the person is proud of their efforts rather than solely their results then they are displaying arête and we must not despise them. This is especially true when someone has put a real effort into something and has failed. (The “competitors” of the Special Olympics come to mind here – it is the effort that is being applauded)
Arachne showed hubris when she claimed her weaving was better than Athena’s. Niobe showed hubris when she said she was better than Leto. Many people show hubris every day when they try to say they are “better” than another because of sexual identity, race or creed; because prejudice is one of the most insidious forms of hubris. All of these things are among the reasons the Gods punish mortals – showing them that they are not better than the one they claim to be above.
We must always remember that the Gods are better than us – as we are mortals – and not just “Think as a Mortal” but ACT as one. True humility, like just pride, is beloved by the Gods. Those who demonstrate it by their actions are beloved as well.