Some socialist systems succeed until their territory gets seized by colonial interests. The US and GB are both guilty many times over of being the predatory belligerent. Most of our wars in the 20th century were about commercial interests seizing the resources of undeveloped nations, and then forcing their populations to work at meager wages.

In fact, when Lenin started his great communist experiment, the first thing Wilson did was unite rest of the industrialized world to sanction the USSR, so (at the risk of sounding like a tankie) we don’t know how well the Soviet Union would have fared if it was allowed to flourish on its own terms. (I don’t expect it would be a perfect utopia, but it may have been able to stave off the decent into corruption for a while.)