I've read a lot of scifi but I'd recommend only one to make sure you get the point: The "remembrance of earth's past" trilogy ( https://en.m.wikipedia.org/wiki/Remembrance_of_Earth%27s_Pas... ) which is more known as "the three body problem". All the books are great but my favourite by a large margin is "the dark forest" (part 2)
I look forward to a day when the top scifi is unabashed optimism about humanity's future.