Cuba functioned by killing everyone who didn't agree. That is one way of confiscating assets. I wouldn't call it functioning though.
The soviet Union functioned by killing everyone that was smart and everyone who looked the wrong way and by creating famine so millions starved and organise slave work. And even after all that in the end it was more expensive to run soviet Union so it was dismantled.
If malfunctioning count as functioning I guess communism works that way.
@freepatriot Weakness is the answer
Yes they have yet to manage to kill the whole population. Not that they aren't trying though