South Africa has an unemployment rate of 27%. The US & UK are at about 5%. There is currently discussion of a minimum wage of R3,500 a month. Half the population earn less than that, i.e. less than $250/£200 a month. South Africa has 89 countries after it on the list of GDP/capita. Even that figure is a half truth, Equatorial Guinea is the "richest" African country on that measure, richer than the UK and France, but less than half the population have access to improved drinking water. That boils down to income distribution. South Africa and neighbouring Namibia are both on the podium for Income Inequality.
I grew up in a bubble. I didn't feel wealthy at all. In my world, I wasn't. Having that bubble pricked by the end of Apartheid opened my eyes to relative thinking. An unemployment rate of more than 1 in every 4 people is a permanent Great Depression. The emotional scars that contributed to the start of WWII through financial disempowerment. It is so intense that many visitors can not cope. So bubbles of prosperity continue. Otherwise they see living next to poverty as the ultimate hypocrisy. The problem is you can't ignore Cape Town by leaving it.
I agree that we need to focus our efforts where we have the best understanding, and that is locally. I learnt, by visiting the United States and Canada, and by living in the United Kingdom that poverty does exist in rich countries. There are mountains to climb, even once there is enough money in creating the kind of world we want to live in. That work can't stop while focus shifts to distant parts of the world.
That said, a lot of perspective can be gained in detaching from what is enough relatively, and thinking of what is enough absolutely. Nothing kills happiness quite like comparison. Nothing kills people quite like war, disease & starvation.