My cousin just told me capitalism was so great, (while I have a more sinister theory about capitalism and why Karl Marx was right in some areas)

Re: third world countries that are capitalist not as developed like United States
Africa and the Mediterranean, for the most part, corrupt politicians made very shortsighted agreements with the USA that doomed them for generations. Central Europe was landlocked while superpowers with the best navies reaped the benefits of dominating the ocean trade routes. Civil war in south American precluded them from uniting and making economic progress.