One does wonder how many girls underinvest in attractiveness, given how common a desire it is, and what the real-world gap is.
That seems like a biased way to formulate the implicit question. Might it not be the case that many people overinvest in attractiveness?
No idea why your comment got downvoted, you raise a valid point. And apart from the issue of over- or underinvesting, for some people the ROI doesn't seem high or even positive.
http://theviewfromhell.blogspot.com/2012/09/toward-non-stupid-non-blank-slatey.html
The author gives a shout out to Less Wrong as a community with a perpetually skewed gender ratio, which is precisely the conditions under which polyandry appears to thrive.
Discuss. :)