I know lots of people in their late 20s / early 30s who get botox.

I personally don't understand it either, but it's definitely a thing.

What are the reasons you've heard your friends give? I don't know anyone who's done it.

They’re very self conscious about wrinkles, in a nutshell, and they think wrinkles make them look old. These are single / actively dating people in a city, too, FWIW.

Self-esteem issues

There's supposedly an increasingly common practice of starting early, so the wrinkles in those areas don't ever develop in the first place...

I imagine it also prevents a more abrupt change later on if you're intending to do it. Going from an expressive wrinkled face to a paralyzed one in your 50s would be much more jarring for your peers, than just lacking expressiveness much of your adult life.

It's all a rather weird form of vanity to me.