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Well, it's kind of like that. In tribal times, the alpha males showed greater chance of survival, by displaying courage, getting food for the tribe etc. Therefore, women would want to mate with those males because their genes would make it easier for their kid to survive.
However, a woman would also want the man to stay faithful since that would increase the resources she could get from him. If the man impregnated more women, he'd have to split his resources with more people. All of this has stayed with us humans for thousands of years until today. That's why people still find masculine, alpha men more attractive than betas. Betas are however more faithful (typically) so they'll commit all their resources to one woman which is why those are still around.
Summary: Alpha males: Better genes and also might give the girl better experiences due to courage, risk taking etc. Beta males: Better providers, generally stay faithful which may pay off with older women.0