Agreed. Its an extension of the Dunning-Kruger Effect. People who truly are good at programming, don't see themselves as 'rock stars'. Its only the shitty developers who would call themselves 'rock stars'.

How do I know if I am a 'ninja' or a 'rock star'? Is it one of those "If you have to ask, you aren't" things?

Do people really call themselves those things? "I'm a rock star developer. I'm a ninja."

Hacker, ok. There's nothing boastful about that term. You could be a really low-skilled but interested hacker.

Its a code word for young. Does anybody disagree with this?

Especially if they use those terms to describe themself.