Suppose that 50% of the time you think someone said something dumb, actually you misunderstood them. This is a good rough guess because it supposes each party is equally likely to make a mistake, rather than the common supposition that other people are idiots and make all the mistakes. Of course if you're a super genius that could tilt the odds, but let's neglect that.
So, half the time you insult someone here's what happened: he said something reasonable, you got the wrong end of the stick, you blamed him for this, and then you lashed out at him. How embarrassing!
I think any kind person aware of this logic must swear off insults.
I recently had an exchange online which could have inspired a post like this.