You think not all that much was done. You have no idea what was done, and neither does your friend. Behind the scenes, tests are being run, consults are taking place, and if you saw an itemized billing statement from the hospital and were qualified to interpret the procedure codes on it, it would reveal that a lot was done. If your friend was in the hospital for six days, something pretty significant was wrong with him because nowadays you don't get admitted as an inpatient unless they're going to give you a brain transplant.
I think a cost accounting of any hospital would be interesting.