The MLMs that work well on social media tend to be the ones related to health and beauty, which definitely target women. The ones that have more males like insurance company ones, Ponzi schemes, cryptocurrency scams or even MLMs like Cutco (knives) or Amway etc tend not to be shilled on social media as much. On top of that, if men do spam on social media, they don't post their MLM shit along with a selfie unlike health/beauty scams (excpetions are the rare "Lulabros" who somehow fell for a women's clothing scam).  Furthermore, pyramid schemes in general like to target people who are particularly vulnerable and more likely to fall for the scam. Stay at home moms are a prime demographic due to potential insecurity that they are not contributing financially to the household, and MLMs are marketed as an easy way to make cash from home, which appeals to that group. So basically there was a huge selective bias in which MLMs I chose (ones with selfies) but despite that, many MLMs preferentially target women so I'm pretty sure it's true that women make up the majority of the suckers who fall for pyramid schemes.