There are things that are worthless-- that provide no value. There are also things that are worse than worthless-- things that provide negative value. I have found that people sometimes confuse the latter for the former, which can carry potentially dire consequences.
One simple example of this is in fencing. I once fenced with an opponent who put a bit of an unnecessary twirl on his blade when recovering from each parry. After our bout, one of the spectators pointed out that there wasn't any point to the twirls and that my opponent would improve by simply not doing them anymore. My opponent claimed that, even if the twirls were unnecessary, at worst they were merely an aesthetic preference that was useless but not actually harmful.
However, the observer explained that any unnecessary movement is harmful in fencing, because it spends time and energy that could be put to better use-- even if that use is just recovering a split second faster! [1]
During our bout, I indeed scored at least one touch because my opponent's twirling recovery was slower than a less flashy standard movement. That touch could well be the difference between victory and defeat; in a real sword fight, it could be the difference between life and death.
This isn't, of course, to say that everything unnecessary is damaging. There are many things that we can simply be indifferent towards. If I am about to go and fence a bout, the color of the shirt that I wear under my jacket is of no concern to me-- but if I had spent significant time before the bout debating over what shirt to wear instead of training, it would become a damaging detail rather than a meaningless one.
In other words, the real damage is dealt when something is not only unnecessary, but consumes resources that could instead be used for productive tasks. We see this relatively easily when it comes to matters of money, but when it comes to wastes of time and effort, many fail to make the inductive leap.
[1] Miyamoto Musashi agrees:
The primary thing when you take a sword in your hands is your intention to cut the enemy, whatever the means. Whenever you parry, hit, spring, strike or touch the enemy's cutting sword, you must cut the enemy in the same movement. It is essential to attain this. If you think only of hitting, springing, striking or touching the enemy, you will not be able actually to cut him. More than anything, you must be thinking of carrying your movement through to cutting him. You must thoroughly research this.
Here's an example from World of Warcraft:
In group content in WoW (i.e. teaming up with other players to kill big monsters — the high-end, maximally challenging game content), one of the key roles is the damage-dealer, or "DPS" (damage per second). One of the DPS classes is the hunter, a ranged attacker. The hunter's job is to deal as much damage to the enemies as fast as possible.
Like all DPS classes, hunters have a wide variety of damage-dealing abilities, with names like Aimed Shot, Arcane Shot, Serpent Sting, etc. Traditionally, damage-dealing classes use their abilities in complex, shifting sequences, called a "rotation", to maximize DPS. (The reasons for this are beyond the scope of this discussion.)
At one point, I was playing a hunter in high-end raid encounters, and consistently performing very well (doing significantly more damage than anyone else). I would often group with other hunters, who were not performing nearly as well. I often had conversations that went like this:
Other hunter: Hey, how are you doing that much damage?
Me: Oh, I just use Steady Shot over and over. Nothing else.
OH: Haha (they think I am joking)
Me: No, seriously. Look at the damage meters. Steady Shot over and over, never use any other ability. That's how you maximize DPS.
OH: That's dumb / that makes no sense / some other similar reply
OH: I still am not doing very much damage...
Me: looking at damage meter You're using Serpent Sting / Arcane Shot / thing that is not Steady Shot. Why? Just use Steady Shot. Literally never hit any other button. I promise you that is how I'm doing it, look at the meters if you don't believe me.
OH: But Serpent Sting does damage over time!
Me: ... it's less damage than just using Steady Shot and nothing else. I can show you the math that proves this, or you can just look at the fact that you are doing the thing you said and doing much less damage than me.
OH: Well, you can do it that way, but this rotation works for me.
Me: gives up
In short, I met many people whom I simply could not convince that the way to maximize performance was to just hit one single button over and over. They insisted on complicating things, gaining no performance benefit and incurring a significant performance penalty. Note that none of these people ever said anything like the following:
"Yes, I realize that hitting Steady Shot repeatedly would maximize performance; however, I find that boring, and so I prefer to hit various buttons, because I find that more entertaining, and I willingly incur the performance hit involved."
These were people who were denied spots in raids (and rightly so!), i.e. denied access to game content, on the basis of their poor performance. They had a clear incentive to improve, yet did not.
But have you ever wondered why so many people are so biased to do something like this?
As a videogame developer.... In reality if you were to go hunting a mammoth, things you traditionally carry would be relevant. Games try to capture that, but this is difficult, and mistakes are made, and something ends up overpowered. Then there's also the health being single variable. In reality there would be different types of "health", whic... (read more)