Most of us do not have enough assets to make this a big deal. After fees, few of us have enough interest income to buy a package of postage stamps.
The theory behind sub-zero interest rates is that people will spend the money rather than pay a bank a fee for storing it.
Fools rush in where angels fear to tread
Negative interest rates are not entirely new. After accounting for inflation, there have been many times when the buying power of savings declined over time.
And while Economists like to dress up in dark, three-piece, pin-striped suits, they are at heart Gypsies in gaudy rags dancing to wild music and peering at chicken entrails. Economics is not the study of money...it is the study (and prediction) of people's actions.
People are imperfect processors of data. Our conscious selves are tiny islands of rational thought functioning in an Operating System that is a tumultuous sea of emotions. That makes the quantitative predictions more than a bit dodgy. Most math is ill-prepared to describe "sticky" behavior.
Mathematically, negative interest rates are a rational extension of the trend to lower interest rates. Emotionally, there is a discontinuity in the "Prospect Curve" when going from gain-to-loss. Discontinuities cause instabilities.
Buddy Holly died in a plane crash in 1959. His death is the basis for the song "The Day the Music Died".
From the official investigation (Wikipedia):
(The pilot Roger Peterson)...was not yet qualified to operate in weather that required flying solely by reference to instruments
Furthermore, Peterson...had received his instrument training on airplanes equipped with a conventional artificial horizon, as source of aircraft attitude information, while N3794N was equipped with an older-type Sperry F3 attitude gyroscope. Crucially, the two types of instruments display the same aircraft pitch attitude information graphically in opposite ways.
So "Up" became down and "Down" became up. But rationally, both graphical formats contain the same information and it does not make any difference.
Robot pendants are the device the programmer holds when programming robots. In most cases, the programmer instructs the robot via a joy-stick inset into the middle of the pendant. If you have ever seen a game system controller you have seen something very close to a robot pendant.
One day, Fred and Barney walked into the Robotics Crib and saw Mick working on a robot pendant. Mick had twenty pendants piled up on the table next to him.
Fred asked Mick, "Whatchya doing?"
Mick replied, "I am fixing these pendants."
Fred said, "I have never seen a broken pendant before. What is wrong with them?"
Mick said, "The joy sticks are installed upside-down. I am spinning them around."
After it was all sorted out, Fred and Barney learned that Mick did not program from the safe position behind the robot. Nope. Mick considered himself an artist and stood in front of the robot, inches from the business end and facing the robot.
The joy-stick was set up so pushing the lever to the left made the robot move to the left....but only if you were standing behind the robot. That was intuitive.
Rationally, it does not make any difference which way the joy-sticks are mounted in the pendant. The programmer still has the same range of motion. But we do not operate in the rational mode as often as our self-awareness tells us we are. We rarely migrate from the emotional Operating System to the simulated Rational System. The cognitive costs are too high and the benefits, usually, are not that much larger.
Mick was creating booby traps. By spinning the joy-sticks around he was creating pendants that would cause the robot to move the opposite way from what the programmers had all been trained. It is conceivable that a programmer could be in tight confines and panic when the robot moved in the wrong direction. Rather than letting go of the joy-stick, they might push it harder, thereby making the robot move faster. A programmer could easily get squished.
Fred and Barney informed Mick that they would break every bone in both of his hands the next time they saw him holding a pendant and a screwdriver at the same time. They were entirely serious.
Sometimes I think Fred and Barney should pay a visit to some of these Central Bankers.