The term 'egomaniac' implies strong negativity and is used to criticize or disapprove someone's behavior. Don't be such an egomaniac; the world doesn't revolve around you!
Pro Tip 2/3
Informal Usage
'Egomaniac' is informal and might be seen as rude or insensitive if used in professional or polite conversations. I would never call my boss an egomaniac, even if it's true.
Pro Tip 3/3
Humor or Sarcasm
Sometimes 'egomaniac' is used humorously or sarcastically among friends or in casual settings. Here comes the egomaniac - ready to talk about himself again!