Sadly we live in a time today with too many self indulged people. But some of us care and try to show our appreciation and understanding back. Manners today are in short supply and it runs the economic and social gambit. So keep doing what you're doing. Half of the boobs in the F cabin will treat any thank you note like a used cocktail napkin but the other half will walk away with a profound respect for you and the other crew members.