No parent wants to support their adult child indefinitely. The whole point of raising a child is to raise them to be self sufficient as adults. There's quite a difference between a parent offering their child a place to stay while they get back on their feet and supporting them "indefinitely".

33 percent of 25-29 year olds live with their parents today: https://qz.com/1248081/the-share-of-americans-age-25-29-livi... It's not rare at all.

For children of immigrants, B is absolutely not a problem, in general (of course there are exceptions). In my experience there is far less stigma attached with living with your parents well into adulthood for children of immigrants than natives. It's even culturally common to remain with your parents until you're married. Of course first generation immigrants have it more difficult. That is part of the inherent risk of moving to a different country.

First generation immigrants were my point in B. Please note that this includes many of your university classmates and current colleagues. They may even come from well-off families who can support them, but they would have to move back to their country of origin and because of the way US immigration works, that would most probably be a one-way trip.

First gen immigrants have it more difficult. No doubt, but at the same time, they start businesses more often than their own children and multi-generation natives do in the US: https://www.forbes.com/sites/elainepofeldt/2013/06/26/first-... . But yes, many first gen immigrants are from relatively well off families in their respective countries. Chances are the immigration policies in the US are more favorable than whatever country they emigrated from. It's perfectly fine that we expect people who come here to work and support themselves otherwise our social programs would get burdened with taking care of anyone who could hop a flight.

Multigenerational living is pretty common in many parts of the world - many places children dont (or cant) move out of their parents house until they are married, and later in life their parents move in with them. There's a difference between supporting a child or parent with a roof and a meal and supporting a child with a NYC apartment and a trust fund.

It is of course a spectrum between no support and supporting a lavish lifestyle. Some parents may be able to let their child sleep on their couch, but cannot afford to rent a bigger home with an extra bedroom. Some parents may be able to afford the groceries, but (after the age of 21) not the health insurance for their child. Some parents may be able to support their child, but with significant financial difficulties that would put a strain on family finances, make their retirement plans nonviable, or pushes back their retirement date significantly; so the child would not dare take financial risks because while they would not go homeless, they will be putting an unreasonable burden on their parents, ...

So yes, if the family is reasonably well-off (owns their home, has savings and good income, have a margin of safety in their finances) you can depend on them as your safety net. If they are not, you cannot or cannot in good conscience.