For example, one could claim that smoking is a reasonable pastime, since millions of people do it. However, knowing the dangers of smoking, we instead say that smoking is not a reasonable pastime despite the fact that millions do it.
While the argument may seem convincing when not examined, a simple refutation would lie in pointing out that at a time not too distant in United States history, it was common to hold other people as slaves, which few people today would consider ethical.
The bandwagon fallacy is a pillar of advertising, along with the appeal to authority fallacy.
See also: Bandwagon effect