You ever felt that people who positively and consciously step on your feelings giving different reasons, actually act totally opposite with others.

You’ve just described part of what makes a Narcissist.

I try to take lessons from that situation.

They're best to be avoided...if once can't physically avoid them, one can try to become immune to them.

I have a manager like that.

Yes. That’s how I grew up.

It's for their ego.

it's good that you recognize that now you need to distance yourself from people like that. personally i have never experienced that but my tolerance for bullshit is very thin