The comment is indeed sarcastic. It seems to imply that the US is not a white supremacist society because otherwise why would white people pretend to not be whi

The comment is indeed sarcastic. It seems to imply that the US is not a white supremacist society because otherwise why would white people pretend to not be white? During a period of racial segregation like the one cited in the comment, people were not pretending to be non-white (the comment used sarcasm again stating "I'm sure that it happened all the time"). So the point of that comment wasn't that being non-white has more downsides than upsides, but rather that people describing the USA as a country where white supremacy is the dominant ideology are exaggerating.