I think ryanwanger's original statement is a sort of a false dichotomy. I don't think you can divide things into "luxuries" and "necessities" without a context. What might be seen as a luxury from one point of view might be a necessity from another point of view.

Drawing on what aspirant said, Maslow's hierarchy of needs is a very good way to provide that context: at the level of physiological needs, you can consider "safety" level needs as "luxuries"; on the other hand, you would consider them as "necessities" from the "love/belonging" level.