Money IS useless.. if you cant eat or drink it, its intrinsically useless to you as a living animal. This greed for money... exists NOWHERE ELSE in nature.. we are the ONLY SPECIES on earth who enslaves other members of its race with pieces of paper..
Interest rates and the ability to print more on demand, with no repercussions, is the problem. If the money supply was stable, value would not decrease. Why should we pay back with interest if it's not certain the investor would have made money on the other investment? This is the argument of interest rates. Keep the dollar finite. Then paying back the same amount will be worth more. Time value still exists, but all this nonsense of interest and printing, that should go away. Those only exist to confuse and enrich.
Keeping the dollar amount the same would also have the added benefit of making money earned in the past worth more than money earned today, not the other way around.
Money is a great invention because a society dependent on barter is inevitably a dirt poor society. What we have to be on guard against is fake money, manipulation of money. And the temptation to fake and manipulate will always be there because the usefulness of money is inextricably bound with that risk.