Here's the logic. Men want women, and do what it takes to get them. They dress nice, improve their grooming habits and obtain a marketable education to secure a high-paying job.
But, this only works in a competitive market. If girls are willing to sleep with guys regardless of merit - if expectations have lessened to the point where girls have sex without any prerequisites whatsoever - then a key evolutionary driver for the male species has been destroyed.
They're not lazy. They're simply getting what they want without the work.
