One lesson that can be learned here is that alcohol and driving/operating any kind of motor vehcilce (Boat, truck, car, SUV, ATV, zamboni, plane, helicopter, etc) is not a good idea. This is a terrible ordeal.
When you make the decision to drive a vehicle with other patrons present (particularly when booze is involved), whether it be passengers or bystanders, you are responsible for making sure that you can operate said vehicle to the best of your ability. Drinking severely decreases that ability, no doubt about it. In this situation, the driver is fully responsible. However, as Fisherman 25 said, all of the people on board also made the choice to be drinking and driving on a boat (or atleast aware the driver was somethat intoxicated) late at night on a lake that is notorious for its hazards. He should be punished, but not hung in a tall oak tree in town square. Bad decision, ALL AROUND. Again, thoughts and prayers to all involved. We all have made bad decisions at some point in time.