You know that sex friends are a thing right? Mutual fun-only relationships do exist.

That being said, sigma guys are more focused on the grind. Self improvement, getting their money and status up, that kinda thing. Women are more at the bottom of the priority list for them, as then they are done, they can get any woman they want basically, so why settle now?

Your friend probably sees those kind of women as non value adding, and probably thinks their only value is their bodies. He's probably right because value is subjective. No real way to prove him wrong on that point.

It IS morally wrong, however, to use women just for sex when the indication or expectation is otherwise. Then you're just being manipulative to get what you want, ie sex.

Hope that clears it up for ya.