Why are you running so dang much?

Over the last couple of months (well except for the 10 days I was on vacation), I’ve been attempting to get my base mileage up.  My weeks leading up to vacation were: 72 km, 58 km, 90 km, and 100 km. Running two weeks over 80 kpw (50 mpw) when I don’t have a long race on the horizon for 3 months might seem like overkill to some, or like I’m asking for burnout or injury.  I don’t think they are, and here is why I’m training like this.