Nobody- You are 100% right consuming so many cups of coffee a day is unhealthy. Cafeine is a form of natural speed, and it is unhealthy for the nervous system (when consumed in such amounts) I am sure. I think this is the down side of drinking coffee, when drinking coffee ceases to become an enjoyable beverage. Nobody this person has an addiction and needs help to wean his consumption.
Do you think he would consider substituting Green or White Tea for some of the copious cups drunk?
Perhaps maybe you could suggest that he make an appointment to see his physcian for an over all examination.