Capitalism is exceptionally good at improving production, to the point where it will eventually put people out of work, and throw a growing number people back into poverty, and that is when a society is ready for a socialist revolution:
When all basic wants can be met, but no longer are solely for the reason of distribution rather than production.
In The German Ideology (1845), Marx warned that an attempt at a socialist revolution in a society that is not sufficiently advanced was doomed to failure as it would just make want common, and class differences would re-assert themselves. No points for recognising the long string of examples where this actually happened.
Every other part of Marxist theory pretty much serves to underpin or expand on that core.