They gained a lot of that wealth by fucking over the rest of the world with superior military power. I'm British, and the British empire was literally 1/3rd of the world at one point. A lot of the infrastructure in Britain which enables to compete favourably against other countries in competitive markets was built off the back of trade in goods that we forced the populations of other countries to produce then took the profits of for ourselves.
I'm not describing capitalism, I'm describing straight up military occupancy and subjugation of the local population. See https://en.wikipedia.org/wiki/British_Raj for example.
If you want a US perspective, then consider Cuba. Would you describe the US embargo against Cuba as capitalism? It's disingenuous for someone to say that countries have struggled because they failed to embrace markets when the US has actively interfered against governments that didn't embrace markets with sanctions and support for coups.
