Ever have that "this person is so close to getting it" feeling? It's all over this thread. At least some libertarians are reachable if you can get them to see that capitalism is unworkable because (among other reasons) it will inevitably lead to the government being bought out.

There's even a highly-upvoted Marx quote to that effect near the top of the thread:

Each step in the development of the bourgeoisie was accompanied by a corresponding political advance of that class....

The executive of the modern state is but a committee for managing the common affairs of the whole bourgeoisie.

Nudge people in the right direction when they're thinking stuff like this.