4 things.
1. Marvel and superhero fatigue. Contributes directly to audiences being bored of going to the cinema because all they see is SUPERHEROMAN or whatever. Hollywood coming out with one mediocrity or remake after the other also contributes to fatigue.
2. Development of tv's. Most of us got good tv's that can compete with the cinematic experience.
3. Covid ruined the social experience of going out to catch a movie. More people got accustomed to staying in their own homes to watch stuff.
4. Subscription based streaming services.