Do you actually care about celebriies?

I was just wondering coz it always makes me feel bad how I don't know who any of these 'celebrities' are and why some people seem to think they're so fantastic. People like Lyndsey Lohan and sienna miller. I know their names from magazines but who are they?! I'm 22 and thought everyone who was trendy knew about this kind of stuff, but I'm not sure anymore.