Going by the manosphere label for K-selected men for expedience.
Think about it. Think about it from the perspective of game theory.
What do they do?
Well, they try to become husband material. Become a good provider, well-rounded man. Stuff that appeals to the future mother of their children. Low time preference qualifiers. They develop themselves into men.
Meanwhile, the r-types are off distracting themselves and ruining themselves in entirely different places (usually clubs) with meaninglessness (sex, drugs, drinking, bragging). This also takes the short-term women out of the picture too. They’re off in the same places. The SMP.
What does that leave?
All these young, fine marriage prospects of women. At their age, other men won’t give them a second look, wanting to have their fun first. In the MMP, a man is rare, and a young one with his life in order too. He has enhanced status and can snap up his pick of the ladies, within reason. She’s young and he gains the most years from her. There is a choice so there can be love.
This takes her out of the market and the single dating pool that cad types will be fishing in later. When they wonder where all the best fish have gone.
It doesn’t seem so dumb from their perspective.
Frankly, it seems quite genius.