Most capitalist countries are not thriving, but capitalism in practise has been around a lot longer than socialism, so it has had a lot more time to evolve and there are more instances of it. It's a numbers and time game. This is how it was always supposed to be, from a socialist perspective, as socialism is meant to emerge out of capitalism, just as capitalism emerged out of feudalism, and feudalism emerged out of slavery. There is still a lot of history to come.

Socialism is the opposite of capitalism, in the sense it seeks to share ownership and control of resources amongst the whole population of a nation, whereas capitalism restricts ownership and control to a small group of people, for whom everyone else must work. Subsequently, socialism has always been a very threatening idea to the capitalist owner class, who rather like their position of dominance and have always sought to destroy socialist experiments with violence, economic blockades, propaganda and other forms of sabotage. This has hindered socialism's ability to flourish in the comparatively few instances where it has been attempted, but the embers still burn and there have still been successes. I see socialism as the economic equivalent of the political franchise. At one time most people could not vote, but suffrage gradually expanded as more people demanded inclusion in the political process, against the resistance of those who had exclusive rights to it. We see the same resistance against the expansion of economic suffrage, but it need not stop it.

Being earlier than socialism, capitalism was also able to capitalise on advances in technology and its unique capacity for ruthlessness, long before any alternative systems reared their heads after feudalism. Capitalism both rewards ruthlessness, and enables the massive accumulation of individual power, through its systems of exploitation. This saw the wealth of countries plundered and people enslaved by the emerging capitalist powers during the European colonial period, and since via more sophisticated techniques of imperialism. For every rich person or country, there are exponentially more poor examples from which this wealth has been extracted.

As I alluded to before, this story does not go on forever. Things are changing all the time. This is but one moment in history.