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
And you cherry-picked movies that disappointed. Of course it is harder to find successful movies once you make the condition of ignoring franchises. Franchises come from successful movies. Valerian's lack of success wasn't caused by it not being a franchise movie. It wasn't a franchise because it wasn't successful enough. There would have been a sequel if it made $500m.
The movie budgets quoted in the various sites do not include the marketing budget. The rule of thumb is to double the quoted budget and compare with worldwide gross.
