They can't.
Hillary's senior thesis was titled, "There is Only the Fight". The pursuit of revolution, deconstruction, and perversion cannot stop, because the pursuit is what gives meaning to their existence.
At some point, of course, the revolution consumes its children and becomes a Stalinist dictatorship (if you're lucky) or a Pol Pot genocidal regime (if you're not) - but that's how the story ends, without fail.
You’re right, the Left can’t stop themselves, but God can.
I’m reminded of 2 Thessalonians: “And now you know what is restraining, that he may be revealed in his own time. For the mystery of lawlessness is already at work; only He who now restrains will do so until He is taken out of the way” (2 Thess 2:6-7).
The Holy Spirit who is in and around God’s people, the Church, is the force restraining the deadly spirit of antichrist which is the driving force of Islamic Supremacy, the DNC and Hillary, and the Left in general. I believe we’re in for a few decades of revival of freedom in America and around the world so Gd can bring in one last ingathering of souls. But after that, we, the Church will be taken up along with the Holy Spirit and then NOTHING will stop the Left.