A huge part of the problem is the public reaction to how for-profit research is supposed to work.
In theory a cure is highly valuable. People should be willing to pay as much for it as the alternative, meaning as much as it would cost for multiple years of ongoing treatment, plus the value of the inconvenience the cure avoids in participating in the ongoing treatment for all those years. A cure should be more profitable than a treatment because patients prefer it to continuous treatment and are therefore willing to pay more for it.
But a treatment that costs $500/week and continues for 40 years is business as usual. Someone offering a cure with a one-time price in excess of a million dollars is derided as a soulless profiteer taking advantage of the sick, insurers refuse to cover it and everyone starts calling for Congress to pass a law against it.
So the market develops treatments instead of cures.