> I wonder if this would get a lot easier with a group. Like, is it easier for 50 people to survive on $100/week of food than for one person to survive on $2.
Yes, and this is basically the financial norm for the poor. Everyone has some money coming in, and the precise amount varies, as does the need for money ("unforeseen expenses in the $20 range"). So large families provide financing internally; when you have less money to hand than you need, you get help from your extended kin, and when you have more than you need, it goes to help your kin.
This is often phrased as "borrowing", but it isn't really; these transfers aren't supposed to be paid back.
When variations in income and expenses are backstopped by a group of dozens of diversified people, you can live right on the edge of your average earning power. When you're a single atomized person, you have more need for a buffer of savings, because your income and expenses are so comparatively erratic.