human and addiction

i wonder why sometimes we humanbeing get so addicted with some of the things we use?
here is a story related with my question;-
i met with a well known musician ask
him atleast to sing for me one song and suprisngly he told me not even asingle line lyrics he could recall.
this made me feel as though i am not type of a guy he relate with,but that was not his fault the problem was that he learnt to sing with a guitor and without it no business!!!