You’re missing fear. Which is a really important tool. Possibly the most important one.
But yeah, happiness, fear, anger and sadness are the basic emotions. But that’s like red, blue, and yellow were the basic colors you used in elementary school painting. You get different degrees and different blends of them and that’s where the complexity comes in. Rage, anger, annoyance? Different degrees of anger. Anticipation? It’s some degree of happiness and fear. Grief? Usually some happiness, fear, and a lot of sadness.
The thing is, placebos can actually be pretty effective. Hell, they’re effective even if you know they’re a placebo. And the more elaborate and similar to what you think would be involved in curing you, the more effective. So people going to chiropractors might actually be getting real results even if the things they’re doing are junk.