Talking about undiagnosable chronic pain conditions, you could drug the sufferer to make them more convenient or you could look at what circumstances in their life make constant pain a viable and often the only possible life strategy. You could even do both at once but somehow the latter option always gets overlooked.
This applies to a host of things. Depression, anxiety, fatigue, ADD, gender dysphoria, chronic migraines, even early-stage diabetes. Try to make the symptom less noticeable (because who cares about the needs of the body, right?) or look at what’s causing it. Controlling the symptom is profitable because you get a lifelong patient. Plus, it works well with the consumerist mentality.
I once developed a condition that inexorably led me to the hospital. I asked myself, “why do I want to be at the hospital? What’s so attractive about it?” The answer was, I was exhausted and wanted to lie down and not move. It’s been 15 years. The condition never came back. I now lie down and not move whenever the fancy strikes, so the condition is unnecessary.