In a nutshell
1) They believe that Black men "failed" them by not elevating them the way they perceive White men have elevated White women. They believe that White women are considered the most beautiful and most desirable and Black women ugly and least desirable not because of anything related to aesthetics, but due to White women being associated with white men, who have more power than any other race of men, and themselves being associated with Black men, who are descendants of slaves.
This mindset fails to explain where White men came from (white women give birth to them) and why no other race of women (Arabs, Native Americans, Asians, etc) treat their male counterparts the same way as Black women do theirs, even though those other races of men don't have resources on par with European descended men and some have similiar histories of being conquered by Europeans. It also fails to explain why...
2) Of the "Big 4" demographics in America (Asian, Black, Latino, White), Black men are the only group in which the men are clearly more desired than the females. Asian women are more desired than Asian men, while White women and Latinas seem to be equally desired as their male counterparts.
The damage is twofold because not only does it hurt their pride (which I can't say I blame them for that - but I do blame them for the way they behave about it), but it also limits their ability to attract desirable partners, which is why a big emphasis is placed on who Black men with money date. The scorn in this case may be more of a case of subterfuge, designed to denigrate and downgrade Black men so they would look less desirable to non-Black women therefore giving themselves better access (for those who want Black men). Also it allows them to play the victim, a victim waiting for a knight (and a White male Knight mostly) in shining armor to rescue them (for those who want White men.)
