The ego can be a very powerful force. How we see ourselves defines our reality... Vanity can be a waste of time but many cling to it and value themselves in odd ways, how much money they have, the cars and clothes that they own. At the end of the day they won't be taking any of it with them when they pass on. Some may regret not having made their life's main focus something different if they have time to reflect when they get old...