You have just encountered Sturgeon's Law. 90% of everything is crap.
Is every podcast full of value, with no fluff? Is every music album? Is every video? No. Why should books be any different?
There are book that are astounding things packed full of revelations. There are books that are the equivalent of a YouTube video that pads a 3s answer to the question posed by its title out to 10min because that's where you start getting better monetization.
There are also books that mostly exist to entertain you with a story. Some of these are great, full of compelling characters and cool ideas. Some of them are not. Some of them have high ambitions of saying something deep about life via a parable. Some of them just want to give you a fun time. Some succeed at whichever of those aims they have. Some don't.
There are books that are introductions to their field. There are books that are aimed exclusively at experts in them. This includes works of fiction - it's a fabulous experience to read a story you're well-versed in, by an author who expects that none of the basic concepts have to be explained to you, and just goes full speed ahead into their crazy takes on them.
Some subjects are honestly not that deep and everything that needs to be said about them can be done in a few chapters. And yet people keep on writing books about the same thing, saying the same ideas in slightly different ways, with a handful of anecdotes showing the ideas in action and other ways to pad it out into something worth paying the basic cost for putting the text through whatever physical or electronic supply chain ends with it in your hands, with a profit for everyone in that supply chain. Sometimes one of these books actually has a new take on the subject. Usually it doesn't.
Find reviewers you trust. If a friend recommends something, check it out; if you think it's garbage after reading it then now you have something to talk about your friend with. Be polite in your takedown of it unless you have shared books with this friend and argued about them a lot in the past. If an author you like recommends something, check it out. Bookstores can provide a curated experience of physical books that you can write snarky comments in the margins of; some bookstores specialize in certain topics, some don't; many will have cards here and there on the shelves with recommendations from the staff. And take chances. If you see a book recommended several times in different context, check it out. If you stumble upon something in the store that looks exciting, grab it. Especially if it's used and cheap. If you find a burning need for that expensive small-press scholarly work on the various jackal divinities of ancient Egypt[1] arises in you the moment you learn of its existence then get it. Especially if most of its absurd price appears in your life while you're still dithering about it. Find communities where people ask for pirated copies of obscure books - sometimes one sounds cool enough to buy for yourself.
Usually a good rule of thumb for fiction is to give it to about page 100. You can quit earlier if you really hate it, life's too short to read bad books, but if a story hasn't grabbed you by that point it never will. Especially beware of any multi-book series where its fans tell you it gets good around book 3-5.
Avoid bestsellers. Except when you don't.
You can always put a book down. Maybe you'll come back to it. Maybe you never will. Maybe you'll put it down so hard that it bounces off the wall and into the trash can. Books are not sacred, books are not all amazing.
1: https://www.darengo.co.uk/product/jackal-divinities-1/ - it's OOP now and I'm definitely glad to have this artifact on my shelves