This passage hinges on the word "afraid". The third "slave" (which is an important starting context) is claimed to be afraid. It is this quality that is then used as a reason for their behavior and eventual dismissal to an outer region.
I'm not in a research place right now to look at alternatives, but suspect that when one has the power to banish, any resistance is going to be claimed as coming from a place of fear. Masters use fear to control and then blame those who stand up to them as fearful. It's a destructive self-referential circle.
Here are three questions that provide an opening through which we can poke at the judgmental character of these end-of-the-year stories:
1) By what means might a slave be expected to double their money?
2) Is not an advantaged slave still a slave?
3) Is not a slave already in a place of darkness?
See this passage through the lens of a fairy-tale with the third telling bringing a needed breakthrough. The benevolent, giving master is now revealed as greedy and demanding. Surely there is a better place to end the year than with the gnashing of teeth.