It sounds like the division is really if you make a living from investments vs. from labor. In that case, a Doctor has invested a lot of time and money into ce

It sounds like the division is really if you make a living from investments vs. from labor. In that case, a Doctor has invested a lot of time and money into certification and skill building, so they make a living more from investment and only partly from labor. Someone who owns apartment buildings is making an even higher percentage of their living from investments, however there is still a labor component to it (maintenance, management, etc). Which can be performed directly by the owner or it may be farmed out to others (which elevates the owner a bit higher in this class).