My friends know the basics and the virtues of saving and investing... because I talk them to death about it.
And yet, despite that, they haven't done it yet. Something about it that makes them stop short of actually doing it.
Of course, they're not alone. I also haven't done my wills yet. My thinking is that I don't have much to leave behind yet, and I'm not sure of the procedure. I know they're just excuses though....