In general it can be said that poor people do not have the capital to make upfront investments which become profitable over time. Not even just literal investing, but investing in things like a more fuel efficient car, upgrading the insulation in your house/apartment to save on heating, buying non-perishables in bulk when there’s a good deal, buying a dish washer instead of hand washing…
So many things that let you save tons of money in the long run, require relatively large upfront investments, that poor people can’t afford. That’s a big reason why poverty can be such an insidious vicious loop, that can be extremely hard to escape from.
Two identical households, with identical income could have vastly different financial situations, just based on if their income was previously low, and they weren’t able to afford any of these investments, vs. If their income was previously high, having allowed them to previously make these large investments to reduce their long term monthly costs, and secure enough liquidity to be able to continue occasionally making these investments.
Fun fact, Spam, as in spiced ham, is actually the origin of the name email spam. There’s a monty python sketch where the name Spam keeps getting incessantly repeated, and based on that sketch the term spam for unsolicited digital messages was coined.