Rome wasn’t build in a day. Capitalism, feudalism, and any other mode of production all took time to develop and then take hold. If you say the first socialist state is the Paris commune, this movement has been around for about 150 years. (It was also fucking dead in the water for decades after the commune’s failure.)

Although history moves faster these days, it’s a little like asking why it took hundreds of years for Rome to dominate the Mediterranean, why it took hundreds of years for landlords to make Europe feudal, why it took centuries for British capital to transform the world. These different modes of production are objectively real. Capitalism objectively produces a shitload of capital. Socialism takes that capital to the next fucking level, as China is beginning to show. Marx was initially wrong (it seems) when he predicted that the first revolutions would occur where capital was most developed; the 20th century shows that it’s much easier to organize the global south against imperialism than it is to organize the global north against capitalism (especially when so many of the global north’s workers are bribed by treats produced by slave labor in the global south). But maybe the 21st century will see the first successful revolutions in the imperial core, after which it’s game over for capitalism.