Here's what I think.
Please note: I'm going to use numbers for emphasis. I have no research basis for these numbers whatsoever. I made them up. If anyone knew what the numbers really were, the entire Indie vs. traditional debate would already be laid to rest.
Let's say 10,000 novelists want to become NYT bestsellers. These are people who have already completed, critiqued, revised and polished their manuscripts, which puts them in about the top 10% of aspiring authors. (Facts are facts. Most people who dream of writing a novel never actually do it.)
Now let's suppose that our authors -- all 10,000 of them -- decide to try selling their manuscripts via traditional publishing methods.
5,000 novelists will succeed in getting an agent. (Of the remaining 5,000, about 500 will eventually sell directly to publishers. The others will give up.)
Of the 5,000 novelists who landed agents, about 2,500 will actually end up with a publishing deal. The others will sit, endlessly waiting to hear back from the agent who is presumably submitting the manuscript to publishers but doesn't seem to be getting any results.
This leaves us with 3000 novelists who actually get a publishing contract, either through an agent or by selling directly to the publisher. For the sake of simplicity I'm going to assume that all 3000 novels eventually see print, although in reality that's unlikely. Publishers go under, deals fall through, and sometimes an author is left stranded.
Ok. So. Out of 10,000 novels, 3,000 have made it through the traditional publishing filters and reached the reading public. Statistically speaking, most of those novels will lose money for the publisher. I'm guessing that about 2,500 of those novels will sell less than 5,000 copies total during their shelf life.
What about the final 500? They sell pretty well. Well enough that the author is offered increasingly lucrative publishing contracts. One or two of them will even hit the NYT Bestseller lists.
So much for traditional publishing.
What if our 10,000 novelists all decided to go independent instead? They upload their book to kindle, smashwords, nook, and every other format they can locate. They promote like crazy online. They solicit reviews and do everything they can to stand out from the crowd. How many of them will reach a sales status equivalent to a NYT Besteller?
9,000 of them will probably languish in obscurity. Let's face it: they're competing not only against all 9,999 other authors who went independent, but also against an unknown number of authors who uploaded to e-readers without bothering to critique, revise, or polish their manuscripts. There's a LOT of content floating around on the internet. It's easy to get buried in the pile.
But. 1,000 of our authors do manage to gain attention for their book and are selling, oh let's say, a minimum of 10 books per day. That's 3,650 books per year, about as many books per year on average as our 2,500 traditionally-published midlist authors. But they're earning significantly higher royalties per book, which means they can actually make a living off their writing, something most traditionally-published authors never manage to do.
Of our 1,000 decently-selling indie authors, something magical will happen to one or two of them. Sales will skyrocket, the book gain national acclaim, and they will reach the status of NYT Bestellers. One or two out of 10,000.
Let me reiterate: These numbers are not real. I made them up. I do not know what the actual numbers are.
But here's the point I'm trying to make: I believe that the number of serious, dedicated authors who make it big through indie publishing methods is neither statistically greater nor statistically less than those who make it big through traditional methods. It's a tough ride either way, and most of us are likely to stumble off to the sidelines puking long before we see any significant money.
I don't think independent authors are any less likely to prove their mettle than traditionally published authors and frankly, I'm tired of listening to aspiring professionally-oriented writers sneer down their noses at indie publishing. Yes, every hack with a keyboard can slap junk onto kindle, but those people were never really in the competition to begin with. Junk won't sell. Good stories will sell. Good authors will sell, and IMO their chances of doing so are about the same no matter which publishing method they choose.