Trump was absolutely correct that Zelensky doesn't have any cards, but as of the fall of Kursk, neither has Trump. It's not his fault, but it is what it is.
- Weapons? Useless.
- Sanctions? Not very effective.
- Direct military reinforcement? Out of the question.
- Kursk? Fallen.
The only thing Putin has to lose is more of his men in the course of the war, but I'd guess the majority of Russian soldiers and civilians believe the fight is worth it at this point. Russia will whoop on Ukraine some more and eventually there won't be anything to negotiate with.
Leftists are outraged by Trump’s attitude towards Ukraine for the same reason they are outraged towards Trump himself: western propaganda has created a false consensus of the reality on the ground. Leftists think Trump is being needlessly deferential to the point of “muh treason” when the truth is that Russia actually holds almost all the cards.