There absolutely are some people who won't buy it, if you play as a woman. Just like there are some people who won't buy it, if you play as a black guy.
I still play Left 4 Dead, and I've certainly noticed how many people leave the game lobby if they're forced to play as Louis (the black guy). They aren't fooling anyone. What's actually happening is, they don't want their friends and family to see them playing as the black guy.
And ultimately, this comes down to something else. Something a little more than a video game. It comes down to the player, or their family, or their friends either not liking blacks, or preferring whites. Like I said, they aren't fooling anyone. It is still discrimination.
Battlefield V has a woman on the cover, and I definitely believe some guys won't buy it due to that fact alone. Because they would be embarrassed if their friends saw them buy it. Like I said, there are definitely people out there who think like that. Some people are afraid their friends, family, etc, would make some kind of joke about a woman, a black guy, etc, being on the cover of their game.
OR, maybe people just don't want to buy it because the game is awful from all the points I've mentioned. It isn't about gender or race, it's about quality.
Tomb Raider is extremely popular, and you know what? It's mostly men that play it. They obviously don't care that they are playing as a badass British woman.
Battlefield 1 was highly commended, even though the cover of the game and opening prologue has you playing as a black guy. Hardly anyone cared, because the Harlem Hellfighters were an actual thing to the war.
The Walking Dead Telltale game was very much liked by players, when in season 1 you play as a black guy, and season 2 you play as a 10 year old girl.
So you see, it's not always about race/gender. Maybe there are close-minded people out there that refuse to play as a non-white protagonist, but it isn't as common as you think. Again, quality over bullshit propaganda like BFV threw at us.