LoL that's so funny - since I discovered the books, AGOT has become more or less my traditional gift for any friend who has even a small amount of fondness for fantasy. I've managed to convert a few of them, even if the size of the series can be daunting.
But I understand your co-worker perfectly - I started reading the series last year and had finished the 4 volumes in less than 10 days. Suffice it to say I didn't get much sleep during that time. And very rarely left home. Even missed a few important classes.
Writing it down makes it sound so much more insane than I thought - it all seemed perfectly reasonable at the time...