Science Fiction shows us the future, always has.
I imagine it started once we as humans started to have an imagination. At that point we could start to imaging “what if?” Both science and creating a good story start with the same question. Also while science must be grounded in reality so must a good story.
Leonardo da Vinci made drawings of airplanes 400 years before the Wright brothers. One of his glider designs was later built and it flew!
In his novel, Twenty Thousand Leagues Under the Sea, Jules Verne describes a nuclear submarine 70 years before the first real Nuclear sub was built. The real one was named after the Nautilus in Vern’s story. It is also 20 years before nuclear power was starting to be discovered.
In other Sci Fi stories various futures are dreamed up. Those futures range from utopia to post apocalypse. What should scare you is that any of them are possible. With imagination the writer has extrapolated what can happen from now till what ever is happening in the story. Some of them are just fluff, violent fluff at that. Some of them tho really are possible. It is those that we should pay attention to. Many of them are social commentary. Others are telling of how past events could replay them selves in the future and how technology may affect the outcome. Next time your watching a show where society is different than our own ask your self how did they get there and what can we do to be like that too, or should we do to prevent it.