Can we talk about what spec fic IS? Because this thread has thoroughly confused me. As I understand it, spec fic is not interchangeable or synonymous with sci-fi or fantasy. It is the examination of plausible, real-Earth (not alt-Earth) futures and the existential questions they entail. Classic examples are the books you'd read in high school English: Brave New World, 1984, Fahrenheit 451, On the Beach, The Handmaid's Tale, The Road. On-screen examples (according to me) include the Matrix trilogy, Black Mirror, Westworld.
Spec fic is to be distinguished from classic/traditional sci-fi (despite the futuristic settings and tech) epitomized by: Contact, Alien, 2001: A Space Odyssey, Star Wars, Doctor Who, etc.
Obviously, the line between is blurry. I agree with Harlequin that it comes down to tone. Works like Jurassic Park and the Hunger Games--while speculative in concept--behave more like thrillers in execution, where the dominant question becomes, "Will they survive?" That doesn't hold much philosophical or moral import, and its scope is very narrow.
I've heard people belittle sci-fi, but never spec fic. In fact, I have only ever heard spec fic referred to in positive terms as a subgenre of literary fiction. Perhaps spec fic is to sci-fi what magical realism is to fantasy.
The one thing I am sure of is that if your story has dragons, it's not "spec fic."