So, in an ideal world, people will only buy real estate and other strong long-term investments, and rather than eating, live off love?
Come on, I didn't say all spending. It's useful to not think black and white, either-or.
Consumption is a vital economic activity. Not just eating, but cars, household goods, anything that either loses value over time, or is consumed by use. People need these things, and you can't just eliminate it, or even really discourage it very much without hurting the economy. Now, certainly we shouldn't encourage
oerconsumption, which is what inflation does, by making less durable goods better investments than just holding on to your money. Demurrage would do the same thing, but to a lesser degree because of it's relative stability and predictability. Certainly it would discourage saving, since that's it's intended purpose.
You consistently confuse consumption with investment and in a most biased way. For you every time something is 'saved' its an investment, and every time something is 'consumed' it's a wasteful act of gluttony and immediate gratification. But every act of investment IS an act of consumption, something which raises aggregate consumption may be doing it by raising investment, it may even be redirection funds from non-investment consumption (the proverbial hookers and blow) towards productive investments.
I've explained that demurrage corrects and diminishes the incentive for immediate gratification by correcting future valuations. Under demurrage it is investment that is encouraged, not consumption for immediate gratification. This has been demonstrated in the few instances ware demurrage has been implemented the populous significantly increased investment activity.
Here is a rather fanciful example of how future valuation under interest is actually causing the kind of waste you seem to abhor. Say I have a Goose that lays a golden eggs and that it will do so in perpetuity. Lets say the Golden Eggs are worth $1000 per year and interest rates are 5%. The Goose is worth $20,000 according to a Net Present Value calculations which is simply per year value divided by interest rates (1000/0.05). If eating the Goose had a value of >$20,000 dollars then the rational choice is to eat it.
Now as you can see the interest rate as denominator means that lowering interest rates makes the goose more valuable, if interest is brought to zero the goose would actually become theoretically infinite in value, which yes is absurd but a perpetual anything is already an absurd fiction so we should not be surprised that an infinite revenue steam has infinite value. Rather it's the opposite that should surprise us, that infinite revenue streams have paltry finite values because of interest.
Now lets try a more realistic scenario, growing a tree for lumber. Trees have finite time to maturity say 100 years and will sell for $1000 dollars. If have to expend $100 dollars to do the planting after which the tree goes on it's own. This is thus a good example to demonstrate how interest effect a long time horizon investment activity because it should be fairly obvious that this action IS a productive investment (for your grandchild benefit perhaps), just a slow one and while it certainly wouldn't be the first thing worthy of funding it can't be called a wasteful act.
Under 5% interest this investment returns $-92 dollars, yes it's actually a massive loss you would have been better off putting the money in a bank and just collecting interest (or spend it on the aforementioned hookers and blow). Why is it so bad? It's because the $1000 dollar payoff in 100 years is savagely reduced by compound interest to a mere $7 dollars. Meanwhile your upfront cost is in the present and is not reduced so profit is 100 - 7 = -92. In fact this investment needs an interest rate less then about 2.5% to just breakeven. Under 0% interest the profit is a cool $900 dollars as our future value isn't being diminished and someone is actually likely to do it as their is a $9 per year return.