Have you ever started a book and put it down after only reading say a third of it, and then picked it up again, perhaps years later, to read it and find you actually like it and now understand it? Mine was Arthur C. Clarke's 'Childhood's End'. The gap between putting down and picking up again was something like 25 years. I was about 15 when first starting it. No slow reader jokes please...
As a kid, the first book I ever read of Jack Vance was a paperback called "The Eyes of the Overworld" that my brother left lying around. (A good part of his stash of books and comics seemed distributed in hidden "pockets" all over the house.) I felt that Vance's ornate and affected style of writing was an annoyingly excessive mire to trudge through, and maybe anachronistic. A couple of years older, the second time around I got it -- the wordplay, what was going on between the lines, the diverting inventiveness. Maybe the first author I ever encountered that I literally read just to enjoy the technique -- didn't care what a story or novel was about specifically. (Barring his early stuff, which lacked that -- that -- whatever it was.) In retrospect, his elan was actually quite suited for the "speculative fantasy" that the "Dying Earth" series slotted into; but he brought that to his science fiction, too -- that's what was distinct.
I think I maybe a bit simple in my science fiction tastes, I don't like too much psychological background on characters, I like the 'hard' science fiction side. Spooky. The point where I first stopped reading was when the Overlords reveal themselves, for some reason back then I thought this was going into science fantasy, here's a wiki description of what my mind couldn't take in. https://en.wikipedia.org/wiki/Childhood's_End#The_Golden_Age It turns out the Overlords had been to Earth in the very distant past, and for some humans, that body image ( Horns, hoofs, wings and barbed tail) was to become the baddie in a future religion. Even the Overlords had ''Overlords''.
The Foundation Trilogy (Asimov) was my introduction to SciFi and of course Stranger in a Strange Land (Heinlein) Who can resists the lure of SciFi after reading these two masterpieces?
That's the thing, though. I rarely, if ever, had a problem with well-touted hard science fiction, even when the characters were often two-dimensional (like Larry Niven's, for instance). Which is to say, I wasn't reading such for the lit merits and the human/social/political value or expecting anything grand, interesting, or innovative in that department, anyway. Circa that general time of youth I also encountered the old movie "2001: A Space Odyssey", and the "retroactively charting on the autism spectrum" Stanley Kubrick's famine of dialogue in it didn't even faze me. Whereas... Just as Aspies probably frequently find themselves shipwrecked on the reefs of the soft category of published scifi, it's not surprising that Vance's wit, aesthetics, and verbal acrobatics would be what scored an overhead whooshing sound on me at that age the first time around. Rather than the ending of something like "2001".
Did you originally disfavor it, though? I could probably recall more novels that I liked as a child that I felt disappointed about years later, than the vice-versa of this topic. That lone instance is all I could remember -- apparently first time dislikes otherwise seem to hang around for me.
Reading the Foundation as a teenager stirred my imagination but it was almost too philosophical to be truly arousing. Only later when having read many more short stories and longer novels did I really start to appreciate the genius of that grand vision.
Funny you mention ''2001: Space Odyssey'', I remember seeing that at the local cinema as a kid, everyone was quiet throughout the film, when the end credits came up the kid sitting behind tapped me on the shoulder and asked '' did you get what that was all about'', honest reply was ''no''. Yet, years later I enjoyed the book and also Clarke's ''The Sentinel'' on which 2001 was loosely based.
I've read more of his non-fiction books than his stories. Asimov's paperback edition of ''Asimov Guide to Science 1, The Physical Sciences'' was the first science book I bought myself. Still got it even though the pages are now falling out.