I am definitely a spoiler averse person, and getting spoiled on things has led me to give up on videogames, questlines in MMOs, Youtube shows, etc.
People will say "well if it's a good story you'll go back to it anyway and it's still good the second time" and sure yeah, but you only get that first experience once. I want to be along for the ride. And getting a bit spoiler can sour my mood and kill my motivation to keep reading. It's not that the story becomes bad, I just... can't care any more. I'm in a bad mood because I lost my "fresh" take.
Rereading a story you know can be a good experience, but it's a very different experience from letting it take your head and lead you around, always wondering what's around the next corner.
And I do have a bit of urge to pick at and guess where the story is taking me, which I can't do if I already know.
I've never read a book by going to the last page first.
I look at the summary to see if it hooks me, then start reading and see if it keeps me engaged. I read a lot of book back covers when I was younger...
And just recently I stumbled onto the WIP book "Child of a Wandering Star", and started reading mainly because I'd already read two stories from the same author and liked them enough to just leap straight into this new one without even a summary.
ETA:
I think a key thing with spoilers is to adjust to the spoiler-comfort of your audience. With my friends I go "hey how do you feel about spoilers on [subject]?" before I start talking about it, and get the go-ahead. And sometimes I okayed them telling me spoilers about something. All the times I was most mad about spoilers that genuinely spoiled my engagement with something? It was unasked for spoilers out of the blue for something I was invested in.