Maybe they don't wanna pay the money, maybe they don't like the new UI, maybe Apple changed features they liked, maybe they're using 32 bit plugins and don't know about 32 lives, maybe they're worried about new bugs from software changes (this is a big reason you'll see people on old as hell versions of Pro Tools, btw).

Plenty of reasons people don't wanna update, bro.

For the longest time I refused to update to Logic Pro X. I started learning on Logic Pro 9 and Logic Pro X just felt so different for some reason even though it was the same software. I eventually updated only because when I updated my mac to capitan Logic Pro 9 stopped working. 

I'm glad I made the update though because not only is the GUI a hell of a lot nicer but there are some features in logic pro X that you can't use in logic pro 9. (At least not to my awareness)

But yeah it's just hard moving on to something different especially when you're used to a certain workflow. Also it doesn't help that there are SIGNIFICANTLY less track color options in Logic Pro X which annoyed the hell out of me for a really long time.

Edit:

maybe they're using 32 bit plugins and don't know about 32 lives

This one as well is HUGE. ^^^ You can't run 32 bit plugins in Logic Pro X without a 32bit>64bit wrapper like 32 lives. (Bye bye Sylenth) I think sylenth might have a 64 bit version now but this seriously prevented me from changing for a really long time until I found out about 32 lives.

Friend also told me that somehow Logic X starts to feel a bit GarageBand-ish. Dunno.

Agree with this, really hoping Apple comes out with support for themes much like Ableton has. But to everyone else, workflow must be the core thing about it. I've known about 32 lives for quite some time now so the 32 bit reason flew over my head.

Most real producers who got on Logic years ago has seen it evolve and love it. Most tend to stick with what they know. Most will try another DAW but cant get use to the workflow and head right back to Logic. Most say that Ableton is great but wished some of the features were in Logic.. I've worked with a lot of them and some are lazy to change and dont have time to learn from scratch!!!