"Researchers seeking to unravel the mysteries of the physiological role of the intriguingly complex Rh system are keen to get hold of Rhnull blood, as it offers the perfect “knockout” system. Rare negative blood is so sought after for research that even though all samples stored in blood banks are anonymized, there have been cases where scientists have tried to track down and approach individual donors directly to ask for blood."
https: //www.theatlantic.com/health/archive/2014/10/the-most-precious-blood-on-earth/381911/
Nah just sick of the pussies who expose themselves as the first that would run when things get tough.