Is it really necessary to know your history?

So a study of 3000 Britons came out that revealed that one in four think Winston Churchill was a fictional character, but Sherlock Holmes was a real person. This article goes on, adding Mahatma Ghandi, Cleopatra, and Charles Dickens as people that some think did not really exist.

I suppose that at some point, a person that is long dead may appear more fictional than real. Understanding history is how to understand why today is today, I think. It's a bit of a shame some folks don't make an attempt to learn about it, but how necessary is it? If you're not that concerned about why things are the way they are (and a lot of people aren't), then why bother learning about history at all?