The sanctions in Venezuela are/were very different from the ones in Cuba, there is a prohibition of trade from any US company and its subsidiaries with Cuba with the exception of food, not some specific sectors aimed at supposedly weakening the government.

With that being said it could also be incompetence and/or corruption, but ignoring the embargo completely is just working to weaken your argument.

It wasnt sanctions but pretty much every extremely oil rich country that is fought over is a basket case, run by a vicious dictatorship or are the sole exception lucky enough to make it work - Norway.

Like Cuba, Venezuela was a poverty stricken mess before the socialists took power.