Why do so many men act like its all about them?

I am talking about guys at work cause nobody wants to date me so i can't talk about dating. But guys at work flirt and lead you on and harass you in multiple ways. They dont stop to think or care how any of their behavior effects me. Its all about them and how they can feel better about themselves. Even if it means putting others down in some way to do it.
Why do so many men act like its all about them?
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