Literary Envy

We are all, let's face it, prone to a bit of envy. In the writing business particularly. Even once you are sure that you have a certain amount of competence and talent - some well reviewed publications and productions under your belt - you still sometimes find yourself subject to bouts of thinking 'why him or her and not me?'
I was mulling this over in the wee small hours because I had been having a discussion with some friends about a certain wildly successful writer - and no I don't mean JK. We all like JK very much, think she's a brilliant storyteller and appreciate all the hard work that went into the books. So although we certainly envy her the cash, we don't envy her the success. Most writers of my acquaintance think it's very well deserved. And curiously enough, although we don't exactly applaud the phenomenon of 'celebrity' publishing, we don't reserve our most bitter complaints for the 'brand' writers - the Poshes and Cheryls and Madonnas of the world. If you've got a brand like that, you're going to exploit it and nobody in their right mind would pretend that the results are great works of literature.
But just occasionally somebody comes along who seems to make it big, really really big, gushing reviews and all, for no very obvious reason . The writer in question, who had better remain nameless, has no claim to fame except the work itself - and the work itself is - dire. There is no other word for it. You try to read it and are reduced to gobsmacked astonishment. Not only that, but I'm reliably informed that this particular writer has a fine sense of his or her own importance and is content to slag off other writers.
I thought it was just me, but then somebody pointed out the reviews on Amazon, and the majority of them said much the same thing, citing reasons. And no, they weren't the kind of moronic, let's-slag-somebody-off reviews you sometimes find. They were sensible, readable, thoughtful reviews. Infinitely better written than the books in question.
You're left wondering how it could happen. Why did nobody point out that the king or queen didn't have a stitch on, not the least little vestige of anything remotely resembling a garment? But then somebody must be buying the stuff or the publishers wouldn't carry on publishing it, would they?
As the incomparable Bridget Jones (whom I genuinely adore) is so fond of saying 'why? why?'