A thinking depression?

Your first post reminds me of how I used to think when I first became depressed in my teens. I thought my dissatisfaction with life was some kind of philosophical revelation. Now that I've dealt with depression for so many years I feel like I'm even more cynical. I don't really believe in dualism anymore.

Meaning comes from my brain. When my brain isn't functioning everything is meaningless and empty. I know because I experience huge fluctuations. If my depression gets bad enough that existential angst grows into something so unbearable it's impossible to describe. There isn't a word for it in the English language. If I'm feeling better I can find enough pleasure in little things. The big picture is meaningless, but that doesn't phase me so much anymore.

You can't think your way out of depression. I can tell that what you're describing is the type of depression I experience, and it can get much worse. You can get to the point where you can't care about anything. You can't get out of bed. You'd kill yourself if you only had the energy to do it. Sorry if I'm scaring you. You really should take this seriously.

Haven't read the entire thread, but the first few posts are, in part, an illusion. Afterall, if you think that you've down the rabbit-hole to realize that life is meaningless, the other side of the rabbit-hole is then, obviously 'Welp, now I can assign meaning to anything' and there should be this richness in your life that had previously been unknown...theoretically. Yet you're stuck in the rabbit-hole.

Your thoughts are reinforcing your emotional states, or occuring alongside them, not causing them. It is an issue I have with things like the idea of CBT. 'Oh, your emotions are responding to your thoughts'. Well, a decade a half of dealing with mood swings, depression, dissociation, memory problems has very clearly shown me that my emotional state, my moods, do not really depend on my thoughts or the events that happen around me. Example: Thought - 'You could go on vacation, a trip somewhere'. 'Normal' emotional reaction I can experience-interest, mild excitement, leading to looking into when I can find time and money to enjoy. Non-functional emotional reaction that I tend to experience - stress on an overwhelming level. The thought is actually 'You could go on vacation'. The emotional reaction varies depending on the mood I am already in. And the opposite does not happen. Like, if I'm happy about the thought, all the planning involved for the trip will itself be enjoyable unless I encounter too many pitfalls for it to happen. I can actually think 'this will be a lot of work' but if I am in a good mood, that will not phase me and could motivate me more. Like, I can tell myself quite obviously lots of negative or positive things, mentally, and they will not actually phase me. The thoughts are not the controlling things.

I sometimes wonder if people's minds don't...supplement reasons for their emotions for them. Minds fill in all sorts of perceptual things when there's not quite enough information, plenty of illusions that are studied quite well know that this happens. It also happens and is studied in people with severed corpus callosums in their brains.
It wouldn't surprise me if minds have a propensity for doing the same thing in response to emotions, automatically coming up with something feasible in the thoughts so that the emotion has congruence and makes sense. I especially wonder if this happens with delusional disorders.