So cynics are three times more likely to live to old age. /cynicism
The other possibility is that cynics don’t have as many close friends, and the lack of strong social connections is correlated to decreased life expectancy. The personality trait causes the lack of social connections.
Or they suffered the loss of partners and family members early, making them cynical. In that case, the personality trait is caused by the environment. The symptom - cynicism - is then blamed as the cause of shorter life expectancy.