I am very much like you. Have you considered, given your minimal value of anything, that the costs associated with recreational drugs don't apply to you? I started (ab)using marijuana this year (daily). It makes life worth it for me. At the very least it's worth considering as an alternative to death.
Its easy to hide. Most the people in my life don't know. You can vaporize to minimize the health effects (also bad breath). If you do it regularly enough the cognitive deficit is less severe. Mostly just occasional memory loss. Again, nothing that you seem to care about anyway.