"depression is often as influenced by external factors as internal ones. A spectacular drug trip won't change the reality of having a death in the family, not being able to find a job after being laid off at 45, or simply the stress of the modern, always-on world."

Have you ever taken hallucinogens? You don't experience a "spectacular drug trip" and suddenly feel better, you actively work on your problems and have a seemingly raw, uncompromising perspective on the external/internal factors that affect your life.

It's a bit like expedited therapy. It's a trying, intentional experience that you have to put effort into in order to get any benefit.