There's also family situations where liquid savings are at risk of being spent by somebody else. I don't think the marshmallow test people factor that in, you'd need to have a third option where the kid waits dutifully for the extra marshmallow but it gets eaten by someone else in the meantime.
Yes. And that doesn't have to be an addict family member or a burglar, it can easily be e.g. a landlord who sees that you have more money, and charges you more money. There are a lot of people in a position to make you give up what you have, if they see that there's money to be squeezed.
This is even more true collectively: as an individual, maybe you can get out by being 50% more frugal than the rest. But everyone can't be 50% more frugal than the rest. If everyone tries, it's even more likely that larger society claws it back through higher rents, lower wages etc.
This. If you’re poor and get money, there are all kinds of people interested in getting a slice, and if you’re a good person, you’ll probably have family members who genuinely could use it for necessities. Govt/creditors can also apply systemic pressure like ”oh you no longer qualify as poor this week, so we’ll take back your benefits”. Well thanks, now I’m poor again.
Employers especially don’t like when people break out of poverty, because as soon as they have a buffer they can make choices and bargain. So there’s a lot of deep pocket incentive to keep people in their place.