If we look at Venezuela from the POV of its oil reserves, Venezuela indeed was ( and still is) one of the richest countries in the world.
Venezeula has been founded as a Spanish colony in the 16th century. In 1811 it gained independence from Spain.
Two things happened: the elites got very rich and the elites got entangled with U.S. interests to such an extent that some considered it a U.S. "colony."
Now to the second part, was it Chavez''s and Maduro's "socialist policies" that made things worse?
Secondly, 2/3rd of country wealth remained in the hands of small very rich elite.
At any rate, what happened in Venezuela has almost ZERO to do with SOCIALISM.