The Left does and believes things not because they think they are right. They do them because they know they are wrong, and they love to see the reaction of those who are Right. It’s what they live for.
You are very close to the target.
They actually have a view on existence which tells them that there is no such thing as right and wrong. This contradicts what God has written on their heart and what traditional Judeo-Christianity teaches so they are conflicted.
To work through their internal conflict, they try everyday to prove that bad things aren’t actually bad and that good things aren’t actually good. They think that by pointing out the imperfections in good things and the value of bad things they will somehow overcome the inherent flaws in the their world view.