It’s not insane, I read aloud to myself a lot too. Especially when a writer has a good rhythm and is aware of the music of their words, much can be gained from reading aloud. Poetry I almost always read aloud. I think the flak you get can be chalked up to it being long associated with the lower classes and people with little education. Same goes for reading with your finger underlining each sentence. Just old fashioned prejudice, nothing more.
The problem is, my best book could be your worst book. No two booklovers have the same taste. If you like good endings I would recommend getting a anthology of short stories from the library. Then you can start to define what you like and what you don’t. You might discover an author who also writes novels, and then you can read one of their novels and proceed from there. In my opinion it’s counterproductive to force yourself to read something that bores you. But I’ve always enjoyed reading, so maybe you’re right that you have to trudge through a book that bores you just to build up your stamina. I do have one recommendation, because it’s really funny and that can keep the pages turning: Hitchhiker’s Guide To The Galaxy by Douglas Adams. It’s also a book that people reference a lot on the internet so you can feel like part of the club after you finish it. If you’re looking for mystery I hear you can’t go wrong with Agatha Christie, though I’ve never read her.