But it does! For example, in Tanzania (the place in Africa that I lived), a lot of women sell vegetables. They don't have enough money to buy them outright at the beginning of the day, so they take them on credit, and then pay for them at the end of the day. The vegetables on credit are very expensive, 25-50% more. The vegetable women is always one day behind, and losing a ton of income because she is being fronted.
If she had enough money to buy the vegetables outright, it would make a huge difference in her life. And indeed, this is the whole problem microfinance loans aim to solve.
There are so many people who just need a very small amount of money ($10-$20), and it would jump start their business.
But instead of saving until they have it, they spend everything they have at the end of the day. And it's easy to see why: when life is very hard, you need something to just feel okay enough to start it all again tomorrow.
Those that end up in a good place are the very people who have the willpower to delay their consumption. Most aren't like that, but some are, and the difference in outcome is stark.
I actually started a school over there, and taught some classes about personal finance, investing, compound interest, etc to a class of mostly young women (young men are much more difficult to teach).
Their minds were totally blown by how powerful even just saving 25 or 50 cents a day. One even told me a year after she attended the class that I had changed her life forever. And indeed I had, she went from having nothing and selling donuts (essentially) on the side of the road, to opening her first small convenience store, to saving money for her second.
These things matter, and there's a lot of low hanging fruit in terms of affecting change in 3rd world countries.