It's a "hits" business though, right? For every person doing $100k/mo, there are how many doing $10/mo?

Indeed. With some experience, however, you can better hit it. I have a friend who never missed it and continues to generate more sales for every new theme he produces.

I'm still skeptical. Kriesi is one of only 2 author's on the site who've earned more than $2MM and <$5MM[0]. He's been consistently adding and updating products for 5 years, so maybe he's breaking $100k/month now, but it's probably closer to $50-80k/month(amortized). Though he'll probably continue to grow and get closer to that.

There are only 11 (of 2492) authors who've earned more than $1MM.

There is only one author (http://themeforest.net/user/ThemeFusion) that really looks like it's near the mark of $100k/month, with between $1-2MM, in just 15 months.

[0]Those numbers are before the network takes their cut of 30% (at that volume). So it appears that nobody on the network is making much more than $60k/month at the top. Of course, that's nothing to scoff at though. But it's certainly not short in time or effort, to achieve that.

ThemeFusion has only one theme. This is a lot different than having a bunch of themes (support and marketing wise)

And that's fair, and is probably what's allowed them to actually come close to that $100k/month figure, before the network takes it's cut. But they're the only one I see anywhere near that figure, regardless of the network. And they look pretty seasoned and focused on that one product.

To even think about that figure you have to be in the top 0.4% of just ThemeForest, disregarding the whole network, because then it becomes much worse.

If you want an achievable goal in any reasonable period aim for $20-40k/month, before the network takes their cut, which goes as high as 50% when you're starting out.

My recommendation would be to follow along with tptacek, and the plan he linked to above.

Don't forget the 50% share that ThemeForest takes, and also the first of sales dates back to 2008.