This is a funny video called, "So You Want To Be a Novelist," but I think it's a little naive. I agree that it's great fun to laugh at people who think of writing as a way to make lots of money, but the person who wrote it clearly thinks Quality Literature = Bestselling Status, and it will not shock you to hear that I disagree.
One specific check to the would-be bestselling author's ambitions is that "your characters are as one-dimensional as the ones in a pornographic movie." You know what sells well? Porn. And when has having one-dimensional characters ever hurt sales of non-porn? I have just finished reading Twilight, a monster bestseller that has been roundly criticized for featuring not just one, but two lead characters who lack anything approaching multiple dimensions.
That criticism is certainly valid: Bella is clumsy. Edward is perfect. Bella loves Edward because he is perfect. Edward loves Bella because she is clumsy. This has led to some angry ranting about the book's gender roles, which will presumably result in a generation of women who think that falling down and nearly getting killed all the time is a sure-fire way to meet Mr. Right. But I used to write jacket copy for paperback romances, and 99% of them have this setup. The woman has zero self-esteem, and the guy is perfect: Rich without being spoiled, good-looking without being vain, brave without being cruel, compassionate without being wimpy, and more than willing to perform unreciprocated oral sex on this woman who enthralls him for no discernible reason.
In other words, it's fantasy. It's fantasy the exact same way porn is fantasy: In romance novels, conventionally-attractive men delight in giving homely women exactly what they want; in porn (at least straight porn), conventionally-attractive women delight in doing the same to equally homely men. The idea is that you, Joe or Jane Average, can appeal to a real winner despite (and this is key) not putting forth effort. You don't have to work at anything--you don't have to tend to your looks, you don't have to be likeable, you don't even have to work up the nerve to ask the person out. You don't have to be Angelina Jolie or George Clooney. You just deliver the pizza or show up to school, and Sexy Perfection Fabulousa will throw him or herself at you. You won't be able to keep him or her away!
There are other fantasies, but most monster bestsellers that I've read hit the wish-fulfillment buttons pretty damned hard. (Some of the funniest bits in How I Became a Famous Novelist are when he's cynically trying to figure out how to hit those buttons.) In most cases, the result is a book that's predictable and forgettable (and maybe a little pathetic).
But not always. The whole Fair Unknown motif, where a seeming Joe Average nobody turns out to be both of noble birth and awesome, has had an entirely respectable and popular run in literature, most recently with the Harry Potter books. Other children's books like the Chronicles of Narnia or From the Mixed-Up Files of Mrs. Basil E. Frankweiler are big on fantasies of autonomy: The kids are separated from their parents, but they survive without any problem and wind up doing totally awesome stuff. Right now, I'm reading Dorothy Sayer's Lord Peter Wimsey books: While what hooked me in Whose Body? was the unexpected departure from the fabulously-wealthy-playboy fantasy, the fact remains that Wimsey thinks nothing of dropping a gazillion dollars on antique books and fine sherry, or running off to Venice on a whim, and that has a certain lifestyle-porn appeal.
So it's possible to have your cake and eat it, too. But don't ignore the mass appeal of porn--we have an Internet today because of it.
ETA: There is, by the way, an economic argument for writing good-quality literature: If it's good, people will continue to buy it, and if it's really good, it will wind up in course curricula, and you will have a captive group of students who are literally required to buy your book every year whether or not they want to, without you spending a dime on marketing. But that's different from producing some big bestseller, and it's a market with its own restrictions (such as a bias toward Serious Literature).
