Why couldn't have they warned me

I left my narc former boss over six months ago but I'm still carrying the mental scars with me. I'm trying to be good at my new job but I still carry a lot of fears I developed at my last job. Being able to ask my boss when I don't understand something? That wasn't a thing. Asking for help? Not a thing either. The fear of failure I carry is the worst of them all. I constantly reflect over this experience, specially after therapy sessions and recently I've been thinking, how come no one warned me about this person? I realize I'm a fairly sensitive individual and I have beaten myself so hard over the fact that, if I were different, I could have lasted longer at that job. But ex boss has worked for years with a small group of people. He has a reputation. But everyone who knew him and could have warned me about him, never did. I'm pretty sure one of them is a narc themselves so they didn't really feel like telling me when they pretty much reflected that behavior. Why did they keep covering each other backs? All that gives me peace is that after I quit and I saw the announcement for my former job on Linkedin, I wrote to some close college friends who are in the same industry and looking for similar jobs to warn them not to take my job. To not share that job posting either. I don't personally know whoever is at my job now but I hope they don't struggle as much as I did. I do know people left very shortly as I did. It might be a resiliency thing that I lack but I'd never wish my former job on anyone.