First of all, the higher your incomes the more your pay. Because of your higher income, you can afford for what you want, so you will go shopping more. In addition, shopping is a kind of entertainment especially for women. it is so funny that i do shopping whenever I'm tired or sad until I'm broken and then i feel better.
Second of all, the sellers have a lot of ways to attract people to buy products such promotion, after sale services, so on. The buyers feel the products are cheaper, so they are willing to pay whether they need or not.