People are less likely to spend money on something completely new now than they were in the past.
I wonder how much of it has to to with the evolving nature of franchises. Before film franchises typically were trilogies. 3 and done. Studios rolled the dice often hoping they had a potential new franchise with a film. If it worked, pump out 2 more and move on.
Now they never-ending. Previously the ones like that were few and far between (James Bond). Now be it Star Wars, Marvel, & DC with their cinematic universes. To franchises that just refuse to disappear like Harry Potter, Fast/Furious, Transformers...etc.
Franchises come and then stay. Forever. Often propped up by overseas audience which seem to have a far more difficult time burning out on franchises than domestic audiences do. Which sucks up the air in the room for new franchises to even have any hope of finding an audience let alone being green-lit.
As much as I love Star Wars I am sure there will come a day where I grow tired and the anticipation is no longer there with the never-ending future of films. You can only have ice cream for breakfast so many times before the fun wears out. But I am sure when that day comes for me the overall audience, especially overseas will not stop. As is the case for nearly every other successful franchise in modern times.