Obsession mystery.

Where does obsession come from? Until recently, whenever Elsie was going on and on about lipstick I would bear with her for a while and then say to her "why don't you use some up before you buy any more new ones?" Sensible frugal me. How naive I was. Now, merely months later, I'm completely obsessed with nail polish. What do you mean, use some up before I buy any more new ones??? There are as many nail polishes in the world as there are colours, plus you have holographic ones and glittery ones and duotone ones, there is really no limit on how many nail polishes I want. Where did that come from? Same thing happened with Jillian. Elsie would rave and rave and I would avoid, until bam, I was all about Jillian all the time. And is it just us? Do other people get all crazy about collecting different coloured stockings and then move on to something else 2 months later, like the search for the perfect tea infuser, and then it's Cranford and then it's tracking calories and then it's wearing your hair in a bun?