First of all, let us note that Belgium is not a socialist economy. Belgium and the United States both have mixed economies. It is true that Belgium has an economic system that is somewhat more towards the socialist side of the spectrum than that of the US, but it is by no means an actual socialist economy.
By living in the US, rather than in Belgium, we get somewhat more economic freedom. What this means is that the government generally has less control over our property than in Belgium. We pay less in taxes. We have to deal with fewer government regulations. This makes it easier for us to do things like starting and running our own businesses. Greater economic freedom is a major benefit of capitalist societies when compared with socialist societies. While Belgium is not socialist, the US still enjoys somewhat more economic freedom than Belgium does.