This answer is nonsensical. Yes there are vast swaths of people who are living in areas that are much poorer than the US. But that doesn't mean we need to measure ourselves based on the poorest of the world.

Does that mean that we should ignore the demands of workers who want a liveable wage of $15/hr in the US? Should we tell them "you're rich compared to most of the people in the world"?

The fact is that we measure "richness" by our immediate surroundings. If we have $50k in savings and we could move to Madagascar and live like a king doesn't mean we're rich, not even in the slightest sense.