Two reasons: it is useful to get guidance for the present and the future, and it's also really freaking interesting. In a different way than physics or math, but still interesting.

While I'm certainly not a historian, more of a history enthusiast, I'd say my interest in history is like an interest in great movies or novels. I'm excited by history, I love reading about it, the stories, the characters, everything adds up to as entertaining as any Hollywood blockbuster or New York Times bestseller.