With me, it's partly that I associate sci-fi with my childhood/early teens. I binge-read the stuff (basically I borrowed from the local library anything with a yellow Gollancz dust-jacket) from the age of ten to about sixteen or so, when I discovered 'proper' books. The only SF book I still own is Philip K Dick's 'The Man in the High Castle', and I very recently read his 'Time Out Of Joint', which begins as an interesting exploration of whether we can trust what we read in the newspapers/see on TV, then degenerates into some silly interplanetary suff, added at the insistence of the publishers.
Apart from watching the first series of Star Trek, and the various Gerry Anderson puppet-based TV series, I've not bothered much with SF films as a genre. I liked 'Dark Star' though.