The real reason why healthcare is so expensive in the US is because Americans want the "freedom" to have everything they want, but expect that someone else should have the responsibility of paying for it. This leads to attitudes such as:
"I want to eat the cheapest and unhealthiest food and drink as much soda as I want, and expect my health insurance to pay for my diabetes, heart disease, morbid obesity, and metabolic syndrome, because it's my right to decide what to eat."
"It's my right to feed my children whatever food I want. How dare the government suggest guidelines for what my kids should and should not eat. How dare they suggest I'm setting them up for a lifetime of poor dietary choices and health problems."
"I want the best health care possible, because I paid my insurance premiums and taxes for decades."
The broader issue here is not that orphan drugs are expensive--to be clear, they are very, very expensive--but that Americans are ignorant and uneducated, distrustful of science yet reliant on science for life-saving medications, smartphones, self-driving cars, nutritious food, clean renewable energy, and so on. They think vaccines are a government conspiracy, believe climate change is a hoax designed to prevent them from getting rich, and believe in a divine Creator that will grant them their wish to be personally wealthy if they simply have enough faith, and that if one does not have their material wishes granted, it is because they didn't give enough money to the televangelist who told them God would answer their prayers. These people complain that Obamacare is too expensive but when they get cancer, expect Medicare to pay for the chemo, radiation, and surgery.
In that context, is it any wonder that health care is expensive? Americans are hypocrites: they preach endlessly about "personal responsibility" but when it comes to actually being personally responsible, suddenly everything is Somebody Else's Problem And I Had Nothing To Do With It.
Drug development is expensive. It costs insane amounts of money to discover candidate compounds, then run through preclinical and clinical trials, then jump the pivotal Phase III hurdles. Orphan indications would never be addressed without giving the pharmaceutical industry an incentive to treat them. If one insists on applying a capitalist economic model to orphan drug development, this is how it looks. You can't claim to be in favor of free-market principles and in the same breath claim that this is the cause of crippling health care costs. This is what Americans ask for when they say that health care should remain a privatized system.