Because they are Leftists. They are the smartest people in the room. They completely lack introspection. They never consider that their emotional decisions and desires may be wrong or even dangerous.
It is why they believe in the Leftist Perpetual Motion Machine that the rest of us with brains in our heads call Socialism. They think that they will do it right "this time".
When they are proven wrong in every damned thing. from economics to international relations to war fighting, they never, ever, Ever, EVER look back. and either learn from their failures or accept responsibility for them.
They simply pack up, move on like union representatives who have gutted an industry and a locale, and go on to the next industry and locale, like locusts preparing to devour someone else's crops while pretending that the failure never happened.
I despise Leftism.
I drove a bunch of folks around on a bird watching excursion a couple weeks ago. Two of them soon found out they were each real died-in-the-wool socialists. As I was driving, I hears about all the evils of the United States and the wonders of Ecuador and it’s communist president. What an experience being able to eavesdrop on those two moronic kooks. If I hadn’t been in such a good mood, I would have dropped them in the marsh at the far back of the wildlife refuge and told them to hoof it out.