Happiness, dopamine, etc are quite temporary. I can still experience them but less and less as time goes on. Looking inwards, understanding myself and getting a good idea about this world, I realize that "Fulfillment" is essentially impossible. I'm quite useless, not completely, but I have nothing to make myself valuable apart from an able body. I'm more and more aware of how flawed human-nature is, but understand it's inevitable.
Still, I'm considering ctb. That's because I'm only living for brief flickers of dopamine and pleasure. I'll certainly miss alot not being here, but I wonder if what I'm missing is worth staying here? After all, life won't be much but base instincts, contributing to the social machine, and hedonism. The overwhelming majority of myself, my soul, my consciousness, just won't be needed. I'd be stuck in my own head, living of food, water, and pleasure.
Certainly, technology will make human life better, at the cost of making humanity itself redundant, and possibly obsolete. I'd prefer to die with dignity as a human, then to have to choose between becoming a machine or becoming a veggie connected to a pleasure machine.