Not every company has this exclusion within the policy, there are companies that put no limits for claims caused by mental and nervous disabilities. This is the exclusion that scares me the most. Nobody, and I mean nobody knows if they will ever become dependant on drugs or alcohol. Most of the drug related claims that I have seen do not come from cocaine, heroin, or marijuana. They come from addictions to prescription medications such as codeine, percacets, and others.
Alcoholism is also so widespread, and can ruin somebody's career at any age.
All it takes is one life event to take a few casual beers a week, and turn it into full blown alcoholism.