A government can profit just by printing the money it spends

Seigniorage is the gap between a currency's face value and what it actually costs to produce — a $100 note costs cents to print, so the issuing government effectively pockets the rest. For coins made of precious metal, the same idea once worked in reverse: mints quietly skimmed a cut by issuing coins worth slightly less metal than their stamped value.

— Wikipedia, Seigniorage — Monetary economics