Is it possible that both Adam Smith and Karl Marx were influenced by the times they lived in... and that modern theories of economics must take into account both human sociology (humans aren't rational actors), upcoming automation, pricing in externalities such as climate change, etc.
Maybe a well designed system could take the best parts of both Marx (min floor, max ceiling, some regulation) and Smith (free markets work for most things) and leave the rest... we need new ideas for a new age.
When automation and AI start to really kick in we will seriously need to think about how to distribute wealth and abundance to prevent over concentration. At some point when the AIs are doing all the work does it make sense to allow some humans to own many orders of magnitude more than others when everyone can be fantastically wealthy?
I'm looking forward to living in the Federation or in the Culture... Sure you can be rich if you want to, if you enjoy playing the capital game you can go live on Ferenginar or somewhere it is played... but everyone has access to abundance and you aren't forced to play the game to enrich others just to survive.