Its not simply "saving". Its where money is so much more valuable tomorrow than it is today, literally no one buys anything because why buy X today when you can

Its not simply "saving". Its where money is so much more valuable tomorrow than it is today, literally no one buys anything because why buy X today when you can buy 2 of X tomorrow? So the economy grinds to a halt. Also, it exacerbates inequality immensely. When deflation is high, it means your existing money becomes more and more valuable for no other reason than existing. So the "rich get richer" in the most literal sense, for no other reason than having been rich in the first place. No investment or risk required.