The convention is if it's magnetic it gets a k (floppy disk, zip disk, hard drive disk), if it's optical it gets a c (laser disc, compact disc, Blu-ray Disc).
So if you want to kick your k's, throw out your hard drives too and live only in the realm of SSDs
I thought the convention was just where it was developed: Americans spell it with a "k", elsewhere it's spelt with a "c": so with IBM being heavily involved with magnetic media it's "disk" and Philips' involvement with optical media meant "disc" became the nomenclature there. That said, I guess it's the way that "program" became the de-facto spelling for computer instructions to differentiate it from "programme" (at least outside the US) which is used for itineraries and stuff shown on the telly. But I still spell both with a "c" since I'm not American and think "disk" looks a bit odd.
Anyway, I still use my DVD contraption often: don't like online authentication, so although I'm losing my CDs and DVDs constantly, I still prefer disc checks; then there's music CDs, videos and a bunch of other stuff that keep it in steady work.