Say you finish building a house. You think one of the nails isn't needed, so you pull it out. The house collapses. You took a huge risk for minor, trivial gains, and it didn't pay off.
What is a way to express this concept? I am looking for a phrase. Or a quote, or sentence, or something similar which would clearly express this.
It is perhaps not a perfect fit, but the basic idea here is that someone is so committed to saving whatever money they can that they don't make choices which are more efficent in the long run.
It is less common (but not unheard of) to apply this phrase to non-monetary situations by analogy - like, "You shouldn't have drilled that hole in the wall. You are being penny wise but pound foolish."
You should let well enough alone, defined by Merriam Webster as:
to stop changing something that is already good enough •I never did learn to let well enough alone.
Also, leave well enough alone. The Free Dictionary says:
The idea behind this expression dates from ancient Greek times, specifically Aesop's fable about a fox who refused a hedgehog's offer to take out its ticks lest, by removing those that are full, other hungry ones will replace them. Put as let well alone from the early 1700s, it was first recorded as let well enough alone in 1827.
if it ain't broke, don't fix it (Wiktionary)
Leave something alone; avoid attempting to correct, fix, or improve what is already sufficient (often with an implication that the attempted improvement is risky and might backfire). I know it’s an ugly looking antenna, but you know what they say: If it ain’t broke, don’t fix it.
"For Want of a Nail" is a proverb, having numerous variations over several centuries, reminding that seemingly unimportant acts or omissions can have grave and unforeseen consequences. ... It describes a situation in which a failure to anticipate or correct some initially small dysfunction leads by successively more critical stages to an egregious outcome.
For want of a nail the shoe was lost.
For want of a shoe the horse was lost.
For want of a horse the rider was lost.
For want of a rider the message was lost.
For want of a message the battle was lost.
For want of a battle the kingdom was lost.
And all for the want of a horseshoe nail.
The cherry that broke the camel's back
This combines 'the cherry on the top', the last extra, easy to put on without much thought, often unnecessary component, with 'the straw that broke the camel's back', the final small part of the burden that causes collapse.
My family have a long history of mashing sayings together, usually opposing ones, to highlight a new truth. I've not heard this beyond my family, but then the OP did not appear to want a 'well known' phrase.
In Jenga, players optimize a tower by removing blocks until it eventually falls. The tower's like the house, and removing blocks from it is like removing nails.
Alternatively, "making the losing move in Jenga" could refer to the optimization that causes the failure.
There is pretty common phrase no one mentioned:
High risk, low reward
These aren't idiomatic expressions/phrases, however the situation could reasonably be described as a cascade failure, where a seemingly small problem triggers progressively larger and larger failures until suddenly an entire system has collapsed. From Wikipedia:
A cascading failure is a failure in a system of interconnected parts in which the failure of a part can trigger the failure of successive parts. Such a failure may happen in many types of systems, including power transmission, computer networking, finance, human bodily systems, and bridges.
It may also be accurate to declare this an instance of Murphy's Law:
Murphy's law is an adage or epigram that is typically stated as: "Anything that can go wrong will go wrong".
An entire building collapsing because you tried to remove a single nail is an extreme example of this.
This is pretty specific :)
If you broaden up the definition:
Took uncalculated risk and found single point of failure (Meaning you didn't know the risk and that decision made everything fail. Notice gain is not mentioned here)
Poor risk management (not 100% showing all the aspects of your description, like how it failed and how much you risked but envelops the concept rather well in only 3 words)
You could say you were oblivious of (or terribly miscalculated) it's risk to gain ratio. (a bit more words but explains more in detail where mistake lies altho still not 100% what you asking for)
You stood to gain little and lost all. (Meaning you could have gained little in the beginning but have lost a lot - altho you didn't know the risk before)
You stood to gain little and lose all and took a chance. (Meaning you knew the odds before making the decision - to gain little or lose it all and you still did it)
Pick your fights wisely! Otherwise, you lose everything.
If it works, you gain a few pennies, and will be tempted to do it again. And again, and again. Until eventually, you are smashed flat.
Related concept:
“Killing the goose that laid the golden eggs”
Refers to a fable (Wikipedia says that it is one of Aesop’s Fables) in which a man owns (as stated) a goose that lays eggs made of gold. He imagines that the goose is simply full of golden eggs, and, in a greedy attempt to get at them faster (rather than waiting for the goose to lay them), he slaughters the goose. Naturally, the goose is not full of golden eggs, and, of course, it never lays another egg.
So, in the hopes of getting at the eggs a little ahead of schedule, the owner destroys a (potentially) eternal supply.
Not quite a perfect fit, but the situation in the question is reminiscent of the concept of unintended consequences (often mentioned as the law of unintended consequences) in economics, politics and other areas. From Wikipedia:
In the social sciences, unintended consequences (sometimes unanticipated consequences or unforeseen consequences) are outcomes that are not the ones foreseen and intended by a purposeful action. The term was popularised in the twentieth century by American sociologist Robert K. Merton.
The Wikipedia article has many examples of catastrophic results of well-intended actions (e.g. the war on drugs, U.S. support for Afghan freedom fighters opposing the Soviet occupying forces eventually leading to the rise of Al-Qaeda and the Taliban, etc.). These are large-scale phenomena that are quite analogous to the question's scenario of the house collapsing because of an attempted small cosmetic improvement.
Don't spoil the ship for a ha'porth of tar. I am not sure of the spelling but a ha'porth is a halfpenny's worth. You might save on tar but if the ship sinks, you will find that it was a stupid economy.
