Allow me. They think they are creating a socialist utopia which requires all the power to be retained by one party, the socialist democrats. They have been successful in retaining power and, they think, they are on the way to utopia. They just have to convince the rest of us and they are home free, despite the facts on the ground.
"...and why they persist ruining it"
They don't think they are, they think they are making it better.
Well it sure as Hell isnt any better. It’s gone steadily downhill for years