An article on NPR.com from April entitled The Sad, Beautiful Fact That We're All Going To Miss Almost Everything explores this idea.
It is the recognition that well-read is not a destination; there is nowhere to get to, and if you assume there is somewhere to get to, you'd have to live a thousand years to even think about getting there, and by the time you got there, there would be a thousand years to catch up on."
Some of us try to make ourselves believe we are well-read, or contain extensive knowledge about the world around us. It is a delusion. It might be true that we have a slightly more well-rounded view than our average peer. But it would be impossible to consume, let alone retain, even a tiny fraction of the liturature and art the world has created just since your birth. You can try to keep up with genres of information you are interested in, but even then you are fighting a losing battle. That doesn't mean we should stop, it just means we should stop pretending that any of us know anything.
I'm sure you all have friends that say things like "You need to watch The Wire.", "You need to read the Dark Tower series.", or "You need to go through Kubrick's filmography." Even keeping up with these personally recomended lists is a daunting task. I'd love to read all the literary classics, but it might have to wait until I retire. There just isn't enough time to be smart. I have a difficult enough time keeping up with the pop culture that society is jamming down our throats every day.