1. 99.9% of people are doing things completely wrong (even most experts and top level professionals) because they hardly ever read, don't have the time to read, don't read enough, or are reading the wrong stuff.
2. The most dangerous things are the things that you don't know that you don't know, and the more you read, the less of these things you'll encounter in life.
3. The more you read, the less you realize you know. Books will humble you.
4. 50% of everything you read in books (and even research journals) is wrong, or only works for certain people, or only in specific circumstances. You never really know what actually works for you until you run your own experiments.
5. The most dangerous thing you can do is live your whole life specializing in only one very narrow field of knowledge, because all knowledge is interconnected and when you specialize you can only see symptoms but not root causes.
6. Sometimes people who read a little are more dangerous than people who never read at all... because they become so obsessed with what little they know that they become oblivious to all the better options.
7. No matter how good you think the ideas in the book you've read are, there are almost always better ideas and ways of doing things.
8. If you aren't reading at least 1 book a day, you're not reading enough.
9. 80% of all your knowledge acquisition should be through books, because... the amount of time, effort, preparation, editing and thought that goes into a book trumps what goes into podcasts, videos, etc.
10. Whatever you read in books is assumed by the author to be true and effective only because it fits their personality type. If you have a different personality type, then what you read may not work for you.
11. (BONUS) There is almost always more than one way to achieve the same end result. Of course, most books will tell you otherwise because they wouldn't sell as many if they didn't...