If you take the sum of all the comments, it goes something like this:

1. Women are disproportionally flocking to a few guys at the very top of the income / success curve. 2. Those guys have amazing dating life, and no pressure to commit. 3. They will go through dozens of women and eventually settle with one. So if they date X women in their bachelorhood, only one 1/X will end up marrying them, and X-1/X will be left disappointed and unhappy. 4. X can be 200+, so that's a lot of unhappy women. 5. Meanwhile tons of guys below the top would love get a date, and can't. They're also unhappy. 6. Evolution isn't optimizing for happiness.