[searine]

The issue isn't a technical one with gene-therapy. The issue is ethical.

Editing your DNA can be dangerous or even deadly if it doesn't work. Modern methods have mostly solved this, but there is still a lot of hesitancy due to prior failures/tragic deaths.

It is also ethically foggy. Somatic edits, edits that will die with you and do not change your sperm or eggs, are one thing, but when you start making germline changes, that impacts everyone who may inherit your genes. You may consent to a germline change, but will your children? Or your children's children's children? You may have the money now to make they change, but will they have the money to change it back?

Small genetic changes also have a complex spectrum of phenotype outcomes. If you start making germline changes that are not found in nature or are under-studied, that can have compounding unintended consequences. For example, if you spec into a dozen intelligence SNPs, that may also increase your risk for a pandora's box of mental illnesses.

So no, economies of scale will not solve this. It would be a disaster.

[condiment]

You're conflating gene therapies vs. the human genome with gene therapies vs. viral genomes. In some cases, the illnesses are genetic, but this article is specifically about how gene therapy companies keep going out of business trying to cure rare genetic illnesses! Even if the technology is the same, the uses are very different and regulatory approval is still required for the application of the technology.

That's not to say there aren't additional ethical challenges that would arise if gene therapies were cheap, but the ethics concerns you're raising seem like future concerns, relevant to a world that does not yet exist.