You seem to think US did this because Maduro was a dictator. They themselves clarified it's because of oil.
Why they don't attack Saudi Arabia then? Saudi's even had a role in 9/11.
Decades of lies shaped the narrative that all invasions US do is because countries have dictators, it's being the narrative even now when they explicitly say it's because of oil.
Oh, I don't think the US should just topple all dictatorships!
If the US could press a button and have all dictatorships automatically become stable, liberal democracies, I'm pretty sure they would do that and we'd all be happy.
But the US cannot just topple the government of all dictatorships at once. If it tried that, it would just cause immense chaos, and all those countries would unite against the West.
The US has to ally with some dictatorships against other dictatorships, like it did with the USSR against the Nazis and how it does with Saudi Arabia against Iran.
Iran hates us since the Islamic Revolution (when we supported the Shah), and finances multiple terrorist groups such as Hesbollah, Hamas and the Houthis. Saudi Arabia is a dictatorship, but at least it's not a revisionist state (https://en.wikipedia.org/wiki/Revisionist_state) and has a more peaceful objective towards its neighbors.
If the US refused to ally with dictatorships, the only country in the entire Middle East that it could ally with is Israel. It would have to fight all other countries at once.
Why doesn't the US take Saudi Arabia's oil then?
They didn't do it because of oil (well to take for ourselves). They did it because Venezuela has been cozying up way too much to Russia and China, and sending both of them a lot of oil.