Is it bad to talk to random people?

I mean on chat rooms? I met few people there, they know how to ask about you in a clever manner but would never tell you about them. When you ask them about their personal life they start asking you other questions. Why is that? I mean, I don't lie about myself but why do those people know how to play this online game so cleverly? I do this when i am bored and when i have no one to talk to.