What's missing in comments:

In developed countries, people buy (or rent) the things they need. Most financial transactions are recorded, taxed, regulated, and with 3rd parties involved at every step (who also expect to get payed). Car insurance, home insurance, electrical bill, etc etc. Grocery prices go up, you pay more. Renting, and rents are raised? Tough.

But in less-developed countries it's not rare for people to grow their own food. They could be living on 0 income & still have food on the table. Swap produce & services with other people in town. No 3rd parties, no taxes (see: informal economy). Build their own home on family-owned land. Insurance? What insurance?

TLDR; there's many flavours & angles on what "poor" or "rich" means in practice.