Wrong Demographic Genius

Why is the 18-24 demographic (or some variation on targeting young people) so “coveted” by everyone who’s selling everything when it’s the baby-boomers who have all the cash (and very little of the consumer debt that my generation is so busy racking up.)

Bonus question: why does the bulk of advertising seem to revolve around men (fast cars, fake boobs, other assorted noise) when something like 90% of ALL PURCHASES are made or directly influenced by women? 

Even lawn mowers.