Except basement dwellers really offends no one, even the people they're said to because it's such a weak insult. Women do get offended at cat lady though

There's also a strong possibility those spinsters are murderous hags with haunted wombs.

Well because single childless women are soon to be a majority of women in the Western World.

The cat lady trope stretches back literal centuries. This is why it wounds them so deeply still, and why "basement dweller" is more amusing than insult to most people.

Unfortunately a lot of times the women/families who can get pregnant easily are usually just as portrayed in Idiocracy and then the liberal brain rot ideals spread