I was paraphrasing a George Carlin joke:

Think of how stupid the average person is, and realize half of them are stupider than that.

true for smaller sample sizes, but for large normally-distributed sets, such as "all people," the mean and median will be pretty much identical. when you take a larger sample, it's more likely that an outlier on one end will be balanced out by a similar outlier on the other end. e.g. when you measure the height of 50 people, you might happen to end up with one person who's 6'8" and have to account for that, but when you measure the height of 50,000 people, you're more likely to also have someone who's 4'4"