Earlier quoted context omitted.
2017 is when I first noticed this... Ghost in the Shell, Valerian, Blade Runner 2049
Care to look up the top grossing movie of that year? There is plenty of successful sci-fi including Star Wars, Jurassic Park, The Matrix, Transformers, The Hunger Games, and Avatar. Every genre can produce flops, but many of the most profitable movie franchises have been sci-fi movies.
You've cherry picked huge hits across decades... I'm saying generally if the budget is >$100million and it's a Sci-fi (not superhero/franchise), it'll probably not be a hit