The original question was why would sociopaths bind themselves by the rules of capitalism, but not by rules of other socioeconomic systems. That's a different question than whether sociopaths' climb to the top can be made useful for others.
Because capitalism rewards such compliance, whereas other socioeconomic systems at the least incentivize breaking the rules, and at the worst punish compliance.
You don't rise to barony by following the rules in feudalism.
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.
Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.
To any future monthly posters of SQ threads, please remember to add the "stupid_questions" tag.