You seemed to suggest in GP that one problem with fiat is that it may become deflationary (ie prices for goods in fiat will go down). I pointed out that Bitcoin is by construction deflationary, prices (in bitcoin) for goods go down as long as bitcoin occupies at least a fixed fraction of total exchange tokens.

Simple example, if bitcoin is the only exchange token in circulation then bitcoin will become more valuable as a function of time simply because the amount of "stuff" increases. This is as opposed to fiat, which increases in supply to compensate the increase of material wealth in the world.

The reason deflation is bad is because it discourages investment. If I can buy more stuff later with the same amount of tokens then I have an incentive to not spend my exchange tokens, thus reducing the total circulation of tokens/investment/etc. It also makes loans more painful (unless interest rates are negative), but if interest rates are sufficiently negative then this encourages people to not deposit money into loan originators (traditionally banks, but in crypto world could be something else).