If something (a commodity) has limited supply and there is non-zero demand => it has a value. Demand for fiat currencies is at least generated by legal tender

If something (a commodity) has limited supply and there is non-zero demand => it has a value. Demand for fiat currencies is at least generated by legal tender laws (you need it to pay taxes). Demand for bitcoin is at least generated by the need to publish some information in a global immutable distributed censorship-proof table. Those two sources of demand are the fundamental ones (I would say intrinsic). There definitely are more. Some demand is for example generated by "store of value" function or "medium of exchange" function. These functions emerge as secondary functions when a commodity is selected by market for its favourable properties. So I would disagree that "bitcoin is not backed by anything". You might have written "I don't see the intrinsic value backing bitcoin" or "bitcoin is not backed by anything tangible". Those statements would be correct.