Something looks fishy, but the author has some unreasonable expectations.
Specifically, if FB is optimizing for click through rate, you cannot expect an even distribution across the demographics. You aren't paying enough to saturate all channels, so you should expect to be mainly shown to whichever segment converts best for your ad.
Specifically, if FB is optimizing for click through rate, you cannot expect an even distribution across the demographics. You aren't paying enough to saturate all channels, so you should expect to be mainly shown to whichever segment converts best for your ad.