Capitalism is an ethically bankrupt system which nevertheless manages to produce very good outcomes over the long term. It does this by redirecting human greed, jealousy, ambition, etc towards endeavors which benefit other people. To be clear: there are plenty of problems, and plenty of people being abused. But compare it with feudal economics, where a rent-seeking class had a monopoly on everything and had absolutely no incentive to improve the economic conditions of their subjects. Capitalism is messed up, but
it works. It works because it accepts as a fundamental axiom that humans are inherently bad.
Compare this with communism, anarchism, etc. They assume that humans are basically good. Let's just increase everyone's income! Except that isn't sustainable unless it makes economic sense. Negative externalities and all that. There's always going to be people that want power and money and prestige. If you get rid of money, they'll seek those things by turning Russia into a dictatorship. Why should they care about the people starving in the holodomor famine? It's an externality.
Note, of course, that capitalism only works well if you have strong human rights and the rule of law. If either of those fail, you get corruption and slavery. But strong human rights and the rule of law aren't going to change the fact that some (many) people will still be working for $2 a day, simply because they've got no better option. The world sucks, but idealism alone can't fix it.
I don't think I'm explaining my point very well, so let me just state it plainly: it's easy to complain about our f^@!$d up system, but much harder to find a solution that works any better. Before you advocate radical architectural changes, you better be able to prove that your revolution won't eat it's young.
This doesn't mean that we get to sit back and enjoy our lives without guilt. I think every person in the first world has a moral imperative to help people in developing countries. However, we need to be realistic about what works. One great way to improve lives is to provide education, or employment for people who complete higher education. Technology provides a good opportunity in this regard (not the best opportunity, but it's something that we can do, without excuse). There's no reason why a Rwandan in Kigali can't earn first-world wages for doing software development.