I've also seen the reverse. Some people who treat me poorly have a terrible voice in their own head where they trashtalk themselves. It's like they see it as fair to do to others as long as they're not hypocritical about it.

Do you talk to yourself the way you talk to me? If so then you need to stop both.

When I was younger I was partly guilty of this and still occasionally catch it. But we are always more sensitive to vices in others that we police in ourselves.