What I think you've been missing the most is the experience of immersing yourself in a book. The way you've been consuming content which is with small nuggets of information is very common today. Most people these days (regardless of age) don't want to invest too much time into content "reading", everyone want the TL;DR, the bullet lists, the KPIs, and in my opinion that this prevents many people to actually discover what is enjoyable about books.
You'll seldom read a book in a single reading session (unless it is very small). If the book is good, it will resurface in your mind, you'll ponder about it between reading sessions. You'll not be engaged with it only when you're reading it, you'll be with it through the whole experience and also after it as it makes an impression in you. By being able to control how the content flows (which is not the same with a movie) you can stop to think about stuff without losing content (this is trickier with audiobooks). You can come back again over paragraphs that made an impact on you and study them to understand why. You an take notes to help you reason about stuff. Lets imagine that take you two weeks to read a book in a casual pace, all that knowledge and content will be with you. The curiosity to know more about it, to get back reading, to learn what happens. That lasts longer, it is a more involved process than consuming video. A good lenghty book might change how you think as you spend a long time with it.
Humans are moulded by the stories they tell and by those they've been told. Books in one form or another have been with us through millennia. They've formed us and will keep doing that in the future in whatever form they evolve to. For me, it is the different of diving deep into something and how wetting your feet in some shallow puddle.
Another important aspect in favour of consuming more books is that there is a chance of reading content by the original author in the original form (or something close to it), which makes it for a more intimate conversation between you and the author. Just stop and think with me for a second, a book is a conversation between you and the author across time and space. You might be reading a long gone author in their original words, getting to know their style, how they thought, what they valued. This is different than absorbing content via a third party which is telling you what they've thought about it, which is the case of podcasts (which I love too, they are awesome but I prefer books). Getting your content from "primary sources" is very different than via third, fourth or even fifth parties.
Even though we produce a lot of audiovisual content on the internet, it doesn't encompasses the whole spectrum offered by books. Yes there are a gazillion videos about Sun Tzu Art of War but there is a lot of longform content that is not popular or clickbaity which doesn't surface through the algorithms used by those social networks we tend to use to discover new stuff. Content from books trickle very slowly to the digital realm. It is like an iceberg, you get a lot of content above the water but unless you're prepared to dive into it, you be missing a ton of stuff. Only very popular information is moved to the internet in a way that it appears easily to people browsing social networks or searching. There are many good stuff that is very hard to find online unless you really know what you're looking for, which makes discovery of such content a bit hard.
I'd urge you to engage with books not because millionaires do it, but because you want to do it. While it is true that some fields move too fast and you'll get the best content about them online. For a lot of other fields, books are better.