They attacked Venezuela because it's ruled by an illegitimate leader who allegedly commands a drug cartel responsible for smuggling cocaine and fentanyl.

It's also not difficult to see the broader strategy: every US adversary (China, Russia, Iran) has been taking a piece of Venezuela over the past several months. They were already "conquered". This could also give the US an upper hand in ending the war in Ukraine as it further weakens Russia as it loses access to cheap oil.