It was the same when I was at school, because we just came to an open and free university from a strict and conservative high school. Girls in high school are basically like this, plain and sloppy, and everyone is like this. Coupled with the heavy school work, basically no girls will compare who bought something beautiful, but occasionally, girls will compete to dress up more.
Going to college is different. I think senior sisters are all glamorous, and no girls are tempted. Who doesn't want to dress up more beautifully, more likable and more conspicuous? And everyone's family situation in college is different. Maybe all the friends around me have good family conditions. After using some kind of skin care water, lipstick feels particularly good, so I will introduce it to girls with ordinary family circumstances.
Girls in ordinary families also want things that can make them beautiful, no matter whether the family is rich or poor. Girls always want what they have, so it's normal for them to start working part-time, then take part-time jobs in their spare time, and then buy what they want with their income.
For example, lipstick, which girl doesn't like, the effect, color and durability of big brand lipstick are not comparable to other brands. Whoever wants a drink of water will lose all the lipstick on his mouth. Who wants to lose all the lipstick on his mouth in a short time? Everyone wants to have a big-name lipstick that makes them beautiful, and parents can only go out to work to earn money to buy it.
Therefore, in my opinion, they are not vain, but at the age of loving beauty, they just have the ability to let themselves have beautiful things.