I'm worried about a close friend

One of my old co-workers recently let himself go, started using cocaine, in abundance, and didn't know how addicted it was, now he's hooked and it's destroying his life.

He's after falling out with a good few people, even his housemate that recently kicked him out, he's been in and out of jobs for a long time, nothing solid and unfortunately he doesn't see anything wrong with his addiction, and he's unwilling to accept that he has a problem.

He's always been very stubborn and doesn't/ never listened to anyone and he always had an ego, a bit of an inflated ego!

It's gotten to a new level recently and parts of his nostrils have been damaged because of the cocaine abuse.

Not a lot of people know about his problem, only a select few, and we found out by default, but we strongly feel like he's wasting his life away, sniff, sniff and more sniffing.

We feel like he might get in with the wrong kinds of people soon and he might begin resorting to crime to pay for his addiction.

We were recently talking to a doctor who works in a rehabilitation clinic and he was telling us that this guy will need at least 6 months or more in a rehabilitation confinement with a lot of help and sheltered from the outdoor public, no temptations and lots of support and guidance.

So I'm unaware and I don't know anything about coke, I've never tried and I never will.

What's it like to be addicted and what steps are appropriate in order to fix the mess?

What's the addiction like when compared to other addictions?