Kevin,
ignorance comes to mind and the fact that they are given those huge bottles for promotional purposes. My dentist has a 1/2 gallon sized dispenser of alcohol containing mouthwash in his restroom.

David - only 10% of people who drink abuse alcohol so that must be factored in.

Immune system integrity as well as environmental factors must be considered as well - many, many variables! Then, as you well know, add HPV to the mix.

Smoking is still considered the leading cause of preventable death.

My H&N surgeon told me it was all a matter of "luck"...