Is their position untenable? If, lacking the resources to place their child into elite circles of society they perceive their child will instead be treated as a vehicle for exploitation, is it irrational for them to withold siring would-be blighted offspring to the world?
I would point out that at least in the US, the degree to which the poor are exploited has been ever-increasing for over a half century with no signs of reversing. If anything, it's accelerating.