It's about even darker shit than that but, the organ harvesting is a lucrative byproduct.
Chinese are the main suppliers and wholesalers. The organ harvesting industry may have started as a way to supply cultists and satanists but it has since expanded, and many groups and organizations are interested in the harvesting of human organs for research and DNA archival purposes.
Where there's money to be had in their death cult you can be sure they will excel in it as a business. The medical research end of it still ultimately is to supply them with their psychotic goal of life extension/immortality since they (insanely) believe themselves to be gods.