Adults in most countries drink some amount of alcohol on a fairly routine basis. Drinking in moderation and making responsible choices while doing so (such as not drinking to excess or driving while drunk) does not present serious risks to other members of society, and it is important to normalize this kind of responsible approach to drinking. If 18-year-olds are not able to drink legally, they are therefore not able to make a responsible choice to drink. This makes drinking a thrill-seeking choice for young adults, which encourages illegal activity and irresponsible behavior. Allowing 18-year-olds to drink legally eliminates the incentive to break the law and establishes the more common, moderate pattern of drinking as the normal and appropriate way to drink.
[P1] Having a higher drinking age makes drinking alcohol more salacious and therefore attractive as an illegal activity.