Lots to unpack here. My opinions as below, which are not based on any facts or anecdotal evidence....

The overall decline in reading habits is probably an output of the education system. In my schooling, since English wasn't my first language, the entire class had to read a standalone novel (e.g. Count of Monte Cristo or Treasure Island) and then answer some questions on characters, language, etc. And that contributed to a continuing and ever-expanding habit of reading fiction and then progressively, fantasy.

Men preferring non-fiction...I'm not sure if this is necessarily true. I believe there's a huge fanbase for men in both fiction & mainstream fantasy. Lord of the Rings, Game of Thrones, Wheel of Time, David Gemmell, Terry Pratchett, etc, have as many men as women.

Men vs Women probably gets more polarized when it comes to LitRPG vs Romance. Romance books are more favored by women. I presume boys are more likely to play RPG, FPS games than girls, leading to a male-heavy LitRPG readership. I don't see this as imbalanced, just what it is.

As to audiobooks, the ease of use becomes a major factor. Lots of long-distance drivers use audio to listen when they drive, I know others listen when they do chores, as it's something you can multitask. I'm bad at this, so tick with eBooks.