"goods will be so cheap that people won't need to work to live."

That sounds like a nice, optimum fixed point. Let's think about how we might get there. It's highly unlikely that things become cheap and then humans lose jobs. It will probably be the other way round. Consider a time slightly before we get to that utopia of yours -- things are not quite cheap enough, but lots of human jobs have been "obsoleted". In such a situation how do the unemployed people survive? How does the system evolve into your utopia, rather than in a direction where the "have-nots" are neglected while the "haves" cater to their own needs? In other words, your utopia looks like a nice fixed point, but it's not a stable or attractive (in the technical sense) fixed point, of this dynamical system.

This is an example which shows that correlation is not enough. It is important to keep in mind what the causes and effects are. You can't have the effect happening first and inducing the cause. The causal order is important.