Governments place taxes on goods such as cigarettes and alchohol as these products are widely used by consumers. The products are addictive, and are dangerous if regularly and widely consumed, so governments see two reasons to tax cigarettes and alcohol;
The products will always be consumed, (unless prices rise above a theshold that would be deemed unacceptable by the public (possibly arising into a black market) so governments are able to place high taxes on these products knowing that it will result in a stable income.
The government can use these taxes to political advantage, as they can say they are placing the taxes to act as an incentive to stop smoking or stop excess alcohol consumption.