I am a non-smoker ,but I have a question on the danger stats of smoking. For example how is it that people?

such as George Burns , Bob Hope, Jack Benny , and Phil Harris lived to be 100, 100, 80, and 91. These guys sported Lucky Strike, Chesterfield, and cigars. Help me understand the stats. It sounds to me "they", those making stats, are taking rats putting them in a smoke filled room locking the door and come back later to find the rats dead. Put a rat in water tank and he will be drowned. So why don't we put the same warning on water?