are differences between countries very big?

I have a cousin that five years had to go to live in the USA, and he started high school there, but nowadays, he is working to get some money for his needs. The other day, he wanted to give me a pair of shoes, but that specific reference cost 220 US, immediately I told him like "you don't buy those shoes, are very expensive, I don't want 1'000.000 COP shoes, that's too much" and then he told me "that's nothing right here, for me it is like 220.000 COP". I realize that being rich in Colombia, is by far, very different from being rich in the USA. Someone getting 25'000.000 COP a month is rich here, but someone with 6.000-7.000 USD is not someone rich in the US, so that is very confusing because returning to the shoe issue, how much money should someone earn to buy 1'000.000 COP in Colombia, which job are they doing? probably they must have at least a professional carrier, but that is not the case in the US, even if my cousin does not have to pay an entire rent or buy all his food, he is just a food deliverer, and he can buy some luxuries, then a question arises. Why should we stay in Colombia rather than be in another country?

Of course, we must fight to change the country's situation, but we have some hard obstacles, in the first place, the corruption, and on the other side, many people of my generation thinking about leaving Latin America.