Yep.
This may not be 100% right, but: think about this -- imagine you're a recruiter who is a partner in a firm, not someone just starting out and getting paid very little. Let's say you place people with average salaries of $100K. Your firm may take 20% of that. Meaning that $300K would only require placing 15 people per year -- that's a little over 1 per month.
Of course, you'd have to share the revenue, pay your share of expenses, etc.
But let's say you can place 2 or 3 per month on average. Or 4, whatever. At some point soon, no matter the expenses and revenue-sharing, your cut should reach $300K.
It may not be so easy to place one person every week or two. But you're working with other people and maybe you have some low-paid people to do the drudge-work of sifting through resumes and so on.
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An interesting point, though, about making those big bucks: the first $300K recruiter I met, some years back, told me this -- yes, you could do well working with him...but he would only hire you if you got yourself trained elsewhere. Meaning, that you'd have take a much lower paying job to start (the number $30K comes to mind, but I don't know how accurate that is -- maybe there are commissions too for successful placements? --- and, in any case, it was a while ago).
So, for at least your first job, you'd probably be working at a large outfit with a lot of people, which might be competitive, with a lot of turnover, perhaps because people wash out or whatever -- whenever I talk to a recruiting firm locally that I've dealt with for a while, most (or all) of the folks I knew previously have moved on.
In other words, you might not make it through the prerequisite needed to get to the $300K guy's firm (and I'm assuming you probably wouldn't start at $300K, or anywhere near that, since you'd be a junior hire).
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The second guy I met who told me he was getting $300K was more recent. He was an internal recruiter -- which struck me as a bit odd, given that he was working for a startup that wasn't very large, so, unless they were to suddenly grow fast, I don't know why they'd need a recruiter that expensive around on a long-term basis, even a very good one.
(It appears he moved on after being there close to a year, so maybe they reached this conclusion too...or perhaps that's the gig -- you stay as long as you're needed then move on -- or perhaps he just found a better position elsewhere).
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But what do I know? I mean, if I really understood recruiting, maybe I, too, would be making $300K as a recruiter.
And, if recruiting occasionally proved to be less interesting than writing software, I'm sure I could come up with ways of amusing myself, such as, say, trolling my candidate-developers by scoffing at the existence of server-side JavaScript and seeing how long I could keep a straight face arguing with them :-)