Generally we should be lowering costs, but if lowering development costs results in more therapies, even if they're cheaper our aggregate cost trajectory could remain the same.

We're an incredibly rich society with a near universal ethos that cost should be no obstacle to life saving treatments, and by extension life prolonging treatments. Despite our many inequities we'll blow millions on treatments that extend life by 5 months. Sometimes (often?) we don't, and it gets roundly criticized as a moral failure, but nobody seriously suggests maybe our target standard of care should be something other than everything possible. (Ivory tower proposals abound but most of us regress to the mean when push comes to shove.) Examples of treatment unavailability that are scandalous here are the norm almost everywhere else, because countries carefully throttle the introduction of expensive therapies at their borders.

In this environment of course our healthcare costs will skyrocket, so long as there's a steady stream of marginally better therapies. We don't need fraud or corruption or misaligned incentives. Those things accelerate the situation and contribute to inequities, but the fundamental trajectory is just perfectly predictable and in a sense unfixable without either changing our shared ethos or fooling ourselves into rationing [future] care by sabotaging the pipeline of new therapies.