Which is the crux of it. Though I wouldn't say it's fair to consider it self-inflicted.
Even if a woman decided she was comfortable with the idea of dating a less-successful/educated man quite a few years younger than herself, few social circles would accept it without friction (far fewer than see any problem with the arrangement were genders reversed) and fewer (desirable) men are themselves comfortable with it.
So, sure, every 20-year-old woman is fairly well aware of these factors and ought to plan accordingly. But even if they shake the mentality at 30, while they can improve their pool, erasing the disadvantage entirely is simply not something that's under their control.