Zolgensma, a gene therapy drug that treats the most common genetic cause of infant and child death, costs $2.1 million dollars for a dose. The disease in question affects 1 in 10,000 babies.

Zokinvy costs it's users around $86,000 per month, and it's used to reduce death risk in those with progeria, which affects around 1 in 18 million.

You can absolutely launch a drug only affordable to the billionaire class, or targeted at an incredibly tiny population. Whatever the market will bear, right?