I just wrote this comparison in a comment on my earlier post about saving society with handcuffs:
Here's how I see it.
Capitalism: high average growth, but with lots of intermediate volatility that enriches some and makes others destitute (generally due to their own choices).
Socialism: low average growth (historically negative) but with less volatility until everything collapses due to demographics.
Basically socialism seems like a graceful way to spend down your societal capital as your society dies off.
I like it enough to it quote myself!