Please look up the difference between private property and personal property. When people decry "property is theft", they're not talking about personal property, they're talking about private property.

Also, socialist states with advanced economies built airplanes, hydroelectric dams and all kinds of complex things. This is a joke of an argument. Say what you will about the living conditions, fairness, corruption or other issues with socialist states, but to pretend they "didn't build complex things" is ridiculous when you look up the number of scientific achievements made first by the USSR.