An ex-neighbour of ours recalled (in an otherwise entirely kind and welcome comment) me telling him, years ago, that my SF novels effectively subsidised the mainstream works. I think he’s just misremembered, as this has never been the case. Until the last few years or so, when the SF novels started to achieve something approaching parity in sales, the mainstream always out-sold the SF – on average, if my memory isn’t letting me down, by a ratio of about three or four to one. I think a lot of people have assumed that the SF was the trashy but high-selling stuff I had to churn out in order to keep a roof over my head while I wrote the important, serious, non-genre literary novels. Never been the case, and I can’t imagine that I’d have lied about this sort of thing, least of all as some sort of joke. The SF novels have always mattered deeply to me – the Culture series in particular – and while it might not be what people want to hear (academics especially), the mainstream subsidised the SF, not the other way round.
A very interestingly informative comment by Iain Banks in an update mainly concerned with his health.