If you give one person $1000 per month, you can improve that person's life with next to zero external consequences. If an organization gives half a million people $1000 per month, the external macro economic impacts must be considered. Societal quality of life improvement is not as simple as in the single-person example. You can't scale one up one to the other and expect the individual result to similarly scale.

If you doubt this true, consider the fact that the US Government currently spends upwards of $1 Trillion /year on welfare programs per year. That is money specifically dedicated to poverty elimination and/or management. An amount that makes the James Web 0.44 billion /year over 25 years look like a rounding error. By your numbers, that $1 Trillion could be used to give each of the ~0.5 million homeless around $1.7 million per year. If it's this simple, why hasn't it been done? Is your assumption about how poverty elimination is as simple as throwing money perhaps incorrect? What do you know that the US Federal government doesn't?

FYI emotional appeals about how a telescope can't help us love each other will do you no favours here. Likewise with implications that you are the only one who cares about homelessness, or that one cannot care about both homelessness and space exploration at the same time.