Socialism has shown to offer benefits in countries with very small populations, a good location for trade with others, and a foundation of infrastructure and wealth generated BEFORE they shifted to Socialism.
Most of the examples being touted as successful Socialist economies are smaller than California in population. Easier to control a smaller country. Supplies have less demand on them, so it's easier for the government-planned production & trade to keep up.
Over time though, the chances of a natural or man-made disaster, economic depression, war among trade partners, or widespread disease could deplete resources beyond their ability to recover. That's when the misery starts. Only the government leaders will not feel the negative impacts.
While Socialism does tend to lean toward a dictatorial or similar government, there have been many countries under dictators with other than Socialist economies. Private property rights is the #1 indicator. Argentina moved toward socialism after taking control of their industries from England. Peron paid off their external debt, improved the economy, had full employment, and so on. The problem with having a period of success is you get careless. They did what we did before the housing bubble burst. Made stupid decisions and over spent until they caused the financial collapse of the nation. After Peron went into exile in Spain, the regime that replaced him became much more of a dictatorship, but fought against factions pushing to establish socialism.