There are a lot of people who are economically marginal but potentially rising with the tide, who suffer a medical ailment or other specific setback, and then end up essentially doomed (along with their kids, etc.). I mean, look at the...50% (? I forget the real number) of bankruptcies caused by medical bills in the US, where even poor people are essentially rich.

Solving someone's one-time problem for $500-1000 and letting him and his family get back to growing along with the rest of their economy seems anything but futile.

By your logic, a person should never try to save another person's life, because so many people die that you can't even make a dent.