In the west, “dating down” often means in attractiveness and/or income. The problem with many western women, they’ve been pumped full of “you’re special”, “you can have it all”, and “you deserve it” narrative so much that they consider themselves a “10”, when they’re a “5”. Then think the average guy is beneath them. If they do date an average guy they’ll still call it “dating down” - when really they’re dating at THEIR LEVEL, they’re not dating a “3” or lower.
This is why many young women think “men are trash”, because they’re all going after the top 5% of men (the “666” men - 6’+, 6+ figures, 6 pack abs) - whom can jump to the next girl in line once they’ve had their fun.
Average guys are checking out from dating. This isn’t going to be good for the birth rate.
If they're going after "666" men (over 6 feet, 6 figure income, 6-pack abs) then you're talking much higher than top 5%. And you are correct, guys like that can have a lineup of girls, and toss each aside when she stops being sufficiently eager to please.