Do the commas in this sentence convey the correct meaning?

I don't think it does make that clear, no. I think it would if you placed that category somewhere other than the end of the sentence, though. For example:

"The vast majority of homeless on skid row are run-aways who willfully chose that lifestyle, drug addicts, and people suffering from mental illness."

You could also make the "comment" about run-aways a parenthetical one:

"The vast majority of homeless on skid row are run-aways (who willfully chose that lifestyle), drug addicts, and people suffering from mental illness."

If you did it that way, I think it would be clear, even if it was at the end of the sentence.

It's a bit ambiguous, sticking in an either or stops that.

The vast majority of homeless on skid row are either mentally ill, drug addicts, or run aways who wilfully chose that lifestyle.

Btw, I doubt most run aways wilfully choose to be homeless, they're normally running away from something much worse.

I don't like that either. I mean, the majority are not run-aways who are drug addicts and people suffering from mental illness. It's kind of late and maybe I'm not clear, but I think you have changed the meaning.

Why don't we change 'and' to 'or'?

"The vast majority of homeless on skid row are mentally ill, drug addicts, or run-aways who willfully chose that lifestyle."

Works for me.

Thanks, but I still don't agree with the author's premise, all sorts of people can become homeless, all it takes is bad luck. What's most concerning is how many ex service personnel end up on the streets.

I appreciate all the replies. Please note: while I created this thread, I am NOT the author of the sentence in the original post. I happen to disagree with the premise as well.

I am battling (rhetorically speaking) on another website with someone who wrote that sentence. My reply to that poster was to say, "I don't believe mental illness is a choice."

His/her reply to me was I needed to learn basic English and what a "comma" was intended for. In other words, the author of the original sentence is saying any rudimentary reading of the sentence can ONLY suggest that it is JUST the "runaways" who are willfully making the choice.

As another poster in this thread noted, that is also questionable (as many runaways don't have choices). But I wanted to see what other folks thought about the original sentence and IF it appeared to them the author was lumping in all groups in that sentence as having made the "choice" to be homeless .

Again, I appreciate the replies.

It might be an idea to say that from the off, you'll get more people on your side wanting to help. The sentence is ambiguous, but that's what people like that are like, they post deliberately misleading, ambiguous statements so they can backtrack on what they actually mean. If you'd agreed that mental illness was a choice weak people make they'd see you as a kindred spirit. Blaming your comprehension is another underhand tactic they like to use.

Good luck, but if it was me I'd just tell them to eff off.

Quite the "conspiracy" theory there, complete with the extra-sensory ability to read minds and all!

Says the white guy with John Lee Hooker's avatar formally known as Hawkeye.

Hawkeye, eh? Heh, yet another demonstration or your remarkable powers of ESP and piercing mental abilities to sniff out the "true facts" behind a nefarious "false flag" conspiracy, eh, Dizzy!?

You use sneaky, underhand tactics like this all the time. One doesn't have to be a mind reader or conspiracy theorist to notice when these same hackneyed tactics are being used time and time again. That's why you were so quick to dismiss my post as conspiracy theory silliness. If you had to be honest you'd have absolutely nothing to say. You're just like a worm wriggling on a hook.

Well, ya know, that post about how and why you would be quick to tell someone you don't know to **** off does kinda help explain a lot of the immediate aggressive intolerance you invariably express.

But, more than just being informative, it's humorous--in a sick kinda way.

Seems very clear to me:

. . . mentally ill, drug addicts, and runaways who willfully chose that lifestyle."
(speaking about the runaways only doing the chosing)

Here's how all three categories would be choosers of that lifestyle:
. . . mentally ill, drug addicts, and runaways, all who willfully chose that lifestyle."

I know the sort, all you need is a sense of smell. It's easy to tell when something stinks, like the degraded black patois straight out of Gone With The Wind you used to spout when you first got here.