Why do some family members never listen to others that give them good advice?

they have a right to live their life any way they want. the more you try to tell people what to do the more they wil do what they want to do. i say leave them alone . if they ask for your help then give it to them but other then that let them live their life any way they see fit . plus your young so in their minds they are thinking you don't know what your talking about