There are plenty of working class parents who support an older child who lives at home. The difference is the child is not pursuing anything, so most parents would not want that for their child and would want him to get a job or something.
My point being that it’s not about finances, it’s not that much more difficult for most working class families to support an extra mouth to feed, especially when it’s an adult. It’s more about the difference in perspective and future financial stability.