I played for a year and a half or so, and I was pretty addicted. If I wasn't working or in class, I was playing warcraft. I made time to sleep every now and then. Hindsight is 20/20 of course, but it really wasn't worth my time--I've yet to play an MMO that is.
Unfortunately, nothing anyone said to me before I came to the realization on my own swayed me. Your friends sound like they're even worse off than I was--I hated raiding to begin with, so I didn't usually schedule things like that in advance. Realistically, you're not going to be able to convince them. They'll probably wake up eventually, so either wait or hang with some other friends in the meantime. Rag on them about it when they come to their senses, but keep in mind that it really is an addiction. Blizzard counts on that fact.
Edit: Oh yeah, one other thing. Don't start playing it just to hang out with them unless you want to become another casualty of warcraft. Once you start, resistance is futile.
Jam it back in, in the dark.
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