Biggest reasons comic book adaptations don’t always directly lead to comic book sales is that long comics runs are tough to get into, most movies aren't based on any singular arc that people would go out and buy, and comics marketing pales in comparison to film and tv marketing https://twitter.com/DHenriquesInks/status/1334461357727604738

Comic book tie-ins do little to encourage people who get into comics because of movies and TV and wander deeper into the comics themselves because the tie-ins have little to do with the comics universe or the movies they’re meant to supplement weirdly. It’s a prohibitive mess!

Every few years, publishers decide to start putting a bit more energy into making comics accessible, but those initiatives only last a little while before Event Comics™ come back to suck up all the air in the room. Cycle repeats itself pretty consistently and comics stay insular