CRISPR technology is used to edit genes. It uses the CAS9 enzyme to cut a small portion of DNA out of a gene and replaces the removed sequence with the desired sequence. This has and will continue to revolutionize biology, medicine, and even wildlife conservation. This technology, if used on viable human embryos, has the ability to make germline edits. That is to say, that once an embryo has been edited, the change is permanent not only for that embryo but also for any offspring of the child resulting from that embryo. This is exhilarating and terrifying because it could treat or even eradicate many genetic diseases. However if it is misused or misunderstood, the effects would be exceptionally difficult to reverse.
I think that although there are definitely ethical questions around using CRISPR on human embryos, the rise of CRISPR-driven market-based eugenics is unlikely. Put another way, using CRISPR, assuming minimal unintended medical consequences, (which is a big assumption I know) would not be much different than eradicating smallpox with a vaccine or saving people’s lives through surgery. It would treat and prevent genetic disease just as we treat and prevent other types of diseases. If a second Eugenics movement arose it would be through poor ethics and social behavior. It would not be a direct consequence of using technology to prevent disease.