There was the big 2017 dip as referenced in this thread but this year is flat in dollars to last year and down about 5% in units.
https://www.comichron.com/
That's the overall trend for years also--dollar volume flat, with declining units.
My quick take on the movies was that they brought all the lapsed collectors who quit in the 90s back into the hobby. And there were a ton of them out there. But that's kind of a one-time generational thing. OTOH, people are living longer and the rich get richer, so I can see even declining numbers of collectors keeping things going (if not setting records). As for the low end, I feel that the internet really helps because people can more easily learn about collecting and what's out there and it's such an inexpensive hobby on the low end. You can get plenty to read and plenty of books for $100 a month.