The alpha/beta dichotomy is a social construct. The only reason women want big muscular men is because society tells them that that's what they SHOULD want. Studies have even shown that women who date less attractive men end up being happier in relationships than those who date meatheades who go to the gym every day.

https://www.maxim.com/maxim-man/why-women-want-ugly-husbands-2017-7
https://www.dmarge.com/2017/07/unattractive-men.html
http://mix965houston.cbslocal.com/2017/09/15/a-study-finds-happiest-relationships-are-attractive-women-with-ugly-guys/
http://www.craveonline.com/mandatory/1321953-study-finds-women-happier-less-attractive-men