Frugality also fits the definition of "theft in the sense that it deprives a producer of the income or potential income that they would otherwise make from someone buying a good." If I were less austere, you could make a ton more money off me.

Also, property is not itself all that metaphysical, at least not if we accept the idea that things actually exist as we perceive them (which seems like the opposite of metaphysics). Some of the trappings we attach to it might be, but property is pretty fundamental to the idea of self. On a very basic level, my property is something I have.