Narcissism
Narcissism comes from broken trust: if no one can be trusted anyway, why not use everyone and feel special? Especially if the alternative is to feel like nothing.
A small child has no reason no tell the truth - it wants things and doesn’t understand that others have feelings, too. Some adults get stuck there: if only your own pain feels real, it’s very easy to lie.
We all have some of that in us. I think about the ways I have hurt others and how long it took to realize I wasn’t that special. And I think about using others to deal with unfinished issues, sometimes without knowing it. It’s easy to make mistakes even if you don’t want to harm anyone.
Then I make the breakthrough: some people hurt me for their own reasons, regardless of who I am or what I do. And others try to care for me. But if I lie myself I’ll never know the difference. Choosing who to trust is my own responsibility.