We should perhaps let Impaler respond, but I feel compelled to comment on this;
you must be punished with a currency that loses value over time, so that you can be encouraged to be as wasteful as everyone else.
I guess that could be put more nicely. The bottom line there likely is not to promote wastefulness, but progress, growth, evolution and all the good stuff.
The idea of accelerating progress through enhancing flow of value is starting to reveal upon me.
Saving is stagnation. In nature, saving achieves little as compared to swift exchange of value. Keeping things stationary - whether material or immaterial - is subject to heavy corrosion. In all things, time eventually eats your value through entropy if you don't use it.
As long as a human monetary system obeys the laws of nature, the same would apply there. It's not difficult to imagine how keeping money off circulation (saving) does discourage initiative and achievement => increasing entropy (= what we generally consider the opposite of "good").
When you save, you aren't holding
wealth stagnant, you are deferring your
claim on that wealth, aka money.
By letting the rest of the world use the wealth that you own (by way of your claim on that wealth, aka your money) until you want to use it, you should be rewarded, not punished. When you come along later to claim your wealth, the natural progress of technology should have made the things you want somewhat cheaper for the world to produce for you.
Demurrage perverts that process in exactly the same way that inflation does. Under inflation, the money you hold is worth less wealth when you want to spend it, then when you save it. Under dumurrage, the money in your pocket literally evaporates, so that you have less of it to redeem when you want to.
Both systems are theft, plain and simple. The difference is that under demurrage, you may have a hard time figuring out
who stole your wealth, while under inflation, everyone already knows.