To provide some context on his aims, Stallman sees money as a malign influence; he lives his own life cheaply so he can concentrate on what's important to him, not what money tells him to do. See this transcript: http://www.gnu.org/events/rms-nyu-2001-transcript.txt

Another thing that Microsoft, well, not just Microsoft, people who don't support free software generally adopt a value system in which the only thing that matters is short-term practical benefits: How much money am I going to make this year? What job can I get done today? Short-term thinking and narrow thinking. Their assumption is that it's ridiculous to imagine that anybody ever might make a sacrifice for the sake of freedom.

Obviously, not everyone's priorities are aligned that way. I'm not sure to what extent he expects the same of other people. But I can at least see where he's coming from.