Way back when, I was going to college and working as a security guard (a lousy one) on a midnight shift. I was at a truck rental outfit and found a bunch of porn novels. In the back of one was a "can you write this" ad, and I thought, hell, who couldn't. So I sent away a chapter on a floppy disk, and next thing I knew I was writing 3 novellas a month for an outfit which sold them by mail order and in Times Square adult book stores. It wasn't a living, but the extra cash was sure nice.
The internet kind of killed that business. For a while, I wrote short stories for any magazine that would buy them, including Penthouse. Yes, sorry to disillusion you, but those letters to Penthouse aren't real. I should know. I wrote a number of them. I discovered some adult book publishers still in operation in the UK. Oddly, or maybe not given the UKs history of corporal punishment in schools, they were all into BDSM in one form or another. I sold novels to Virgin (Nexus), Olympia Press, Silver Moon, and Chimera. Then they all sort of dried up and I wound up selling my first ebooks through BDSMbooks.com. All the while holding down real jobs, of course, to supplement my income. Or maybe it was the other way around. Until lately, my jobs earned more than my writing but with erotica/porn going more mainstream and being sold on Amazon, Barnes & Noble, and other sites, with generous returns (70% at Amazon) that has reversed and I now earn considerably more from writing than from my job. Let the good times roll, and continue. :-)