Because luck is what you need, Lydia. (Tl;dr – failed ‘proper’ novelist announces intention of writing ‘porn’ to make a big pot of money.) Whether luck is what you deserve, what with your smug, thick, condescending attitude, I wouldn’t presume to say.
The idea that anyone who is a proper writer can debase him or herself by ‘churning out’ (as they invariably put it at some point) sexually-explicit fiction and earn a good living is one that’s been around for decades, and may even have been close to the truth at some point. It’s certainly nowhere near the truth now, as 99.9999999999% of 50 Shades bandwagon-jumpers have been finding out. It wasn’t true in the late 90s when it was a teeth-grittingly annoying chick-lit trope, probably influenced by the launch of Black Lace a few years previously (minor character’s Shocking Secret is that she writes erotica and therefore has an embarrassingly large sum of money in the bank). Two otherwise fairly enjoyable books that are slightly spoiled by this (for any erotica author reading them, anyway) are Fiona Walker’s Well Groomed and Jumping to Conclusions by Christina Jones. Even then, no one was actually making that sort of money out of erotic fiction, though the authors writing it at the time were generally enjoying themselves rather than holding their noses and tossing their books out into the world with great disdain.
From time to time, some or other unsuccessful ‘literary’ novelist will announce his/her intention of lowering him/herself to write genre fiction as a way of raising his/her income. If s/he is moderately connected, there may be a slight flurry of interest initially, but it probably won’t translate into much in the way of sales. This is at least partly because the reason the literary novelist is not selling much in the first place is less to do with the world being a coarse, vulgar place full of oafs who no longer appreciate fine writing, and more because s/he can’t tell a decent story and has fuck all to say apart from ‘Look at what a wonderful writer I am’.
If you despise your own work and your target market, it will actually show. EL James, for all her freakish Lottery-winning good luck (and crimes against the English language) did actually have some genuine enthusiasm for her derivative, heteronormative wank fantasy. She must have done, to have spend all that time messing about with it on fanfic sites, way before she ever made a penny from it.
Most of all, though, the way never to sell a book again is to tell potential buyers that it’s rubbish but all they deserve. As with any other product, it’s a poor idea to insult the client. Remember how that went down for Gerald Ratner?