Not a Marxist but the ideology evolved over time. In time where Karl Marx wrote his books capitalism was legitimately dehumanizing (12 hour work shifts in metal processing plant good luck), in his time he believed that the classes were split into the ones with capital which would be landowners, petty bourgeois who had money but not much land or workforce who would soon be pushed out by the upper class , and a working class. You cannot apply this as time went on now that tech giants dominate the wealth charts, mega corporations like Disney or Nestle exists, it's much harder to target a certain class now