For so many families, the only way they can afford to support their children even in their childhood is government aid, which gets cut off when the child reaches 18.
B. For immigrants, moving back to one's parents is a much more difficult process. You may have to move to another continent. You have to give up on trying to find a job or settle down in the US. Moving back to the US afterwards would not be exactly easy either, because being away from the US for extended periods of time may mean losing your green card.
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.
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.
I think this comment is (no offense intended towards you specifically) very indicative of how insulated and lacking in diversity tech is.
40% of young adults in the USA do live with family, and it’s a good bet that a large fraction of the rest could. It’s certainly not universal by any means, but it’s also far from some great rarity.
https://www.cbsnews.com/news/percentage-of-young-americans-l...
I’ll grant that the original comment talked of having “his own bathroom” and that is reasonably rare, but it’s the least important part of the package compared to a room and shared meals.
A room and a meal indefinitely with absolutely no pressure to leave or contribute? With the freedom to find the next job or opportunity that fits, not just desperately throw out their resume and accept the first offer? Not so much.
Like I said in another comment even in the poorer European countries it's possible to move back with one's parents. And in fact people do live with their parents into their twenties.
The fact is, having parents with a place you can crash at is perfectly normal. If your parents weren't complete degenerates or very unlucky, they have a couch you can sleep on. Anybody who's startup founder material can at that point find themselves a job.
I also didn't mention location, but my relative's parents are withing spitting distance of the valley. Someone who has to move from Mountain View to Omaha is going to find it really hard to get back into the thick of things.
People growing up in Omaha are at a severe disadvantage vs people who grow up in Mountainview.
And if your parents are in Mountain View or nearby, you can stay with them a few extra years after you get your first job to save money for a downpayment on your own house.
A person without that option may spend a decade paying rent and trying desperately to save up enough for a down payment.
In most places in the United States, extra space is a premium that requires consistent stable work at or above the median household income in a single field of work over extended periods of time.
From this alone we can rule out those who work minimum wage jobs, most of those who do not have an established field other than "Service Industry" and many of those who specialize in an "unskilled" trade, e.g. forklift operators.
Those who do manage to purchase a home with the requisite space often don't live in posh neighbourhoods with comfortable amenities, and generally are not swimming in excess income.
Additionally modern society, with its' inundation of appealing marketing campaigns and easy credit, has rendered even your "middle class" families cash-poor, stretching their budgets thinner and thinner with each additional monthly payment.
When you culminate all of these things together with a fundamental breakdown in nuclear families and rising divorce rates, "going home after a rough patch" is not an outcome most are able to, much less willing to, consider.
It's the privilege argument that I'm sure you're sick of arguing about. The world is set up well for perfectly ordinary middle class educated kids with working (or wealthy) parents. That's not everyone.
If you're somewhere in the lower or middle "middle class", the world still isn't set up very well for you.
Being of the "cultural upper middle class" (born into a professor, scientist, engineer, etc. family) is also an advantage.
Do you mean an extra bedroom with two or more beds for your kids or an extra bedroom per kid? That makes the difference and it is more uncommon.