I got introduced to Linux back with Ubuntu 8.10 and shortly thereafter discovered Kubuntu with KDE. I've tried the others, but still always come back to KDE. When KDE 5 came out on Kubuntu, I gave it a try, but had issues with Dropbox working. Hopped around several distros, before finally settling on Mageia 5, which uses KDE 4.
So I've been using KDE 4 in one form or another since 2008 or so. It works for me, and I know how to use it. I like how familiar everything is eight years later.
I'm at the point in my life where I want it to "just work", and quit changing icons and programs around just for the sake of it. My Galaxy S5 just updated the icons yet again, and introduced new programs I don't want.
As the mainline distros switch to KDE 5 I'll probably be forced to upgrade, but in the time being, going to ride the KDE 4 train as long as I can.