Because of that, it is economical to spend lots of time optimizing it, even if it only makes the code marginally more efficient.
Pipes aren't used everywhere in production in hot paths. That just doesn't happen.
If 100 million people each save 1 cent because of your work, you saved 1 million in total, but in practice nobody is observably better off.
Obviously not if you are doing for your own fun or just improving the state of art.
You don't need the effect to be observable on an individual level
It's something that is worth an engineer's time
Also, if you micro-optimize and that becomes your whole focus and ability to focus, your business is unable to innovate aka traverse the economic landscape and find new rich gradients and sources of "economic food", making you a dinosaur in a pit, doomed to eternally cannibalize on what other creatures descend into the pit and highly dependent on the pit not closing up for good.
I admit my opinion is not based on first hand knowledge, but I have for years worked on projects trying to address poverty at different parts of this planet and can't think of a single one where this would be even remotely true.
My opinion, however, is based on first-hand knowledge. I've been the kid saving those pennies, and I've worked with those kids. I understand that in the vast majority of cases, an extra penny does nothing more. That isn't what your original comment above claimed, nor is it what you've claimed here. My counterexample is enough to demonstrate the falsehood. Arguing that there are better ways to distribute these pennies is another matter, and I take that seriously as well.
Assuming a wage of $35/hour, each second is worth 1 cent. To save 1 cent you only need to reduce the time spent waiting for computers by a second across the entire lifetime of that person.
Now here is the beauty of this. There isn't just a single guy out there doing this. There are hundreds of thousands of people, possibly millions, doing it.
The average human life expectancy is 77.5 years, or 2.4457e+9 seconds. If you divide that by, say, 1 billion daily active users of Google, you get 2.445. So if you work at Google, and optimize a slow process, and save every user 1 second, once, you've saved 2 lives. If you're a Microsoft and make boot up take 1 second less across their billion or so devices, same thing.
https://en.m.wikipedia.org/wiki/Synchronous_grid_of_Continen...
You are a few logical layers removed, but fundamentally that is at the heart of this. It isn't just about what you think can or can't be leveraged. Reducing waste in a centralized fashion is excellent because it will enable other waste to be reduced in a self reinforcing cycle as long as experts in their domain keep getting the benefits of other experts. The chip experts make better instructions, so the library experts make better software libs they add their 2% and now it is more than 4%, so the application experts can have 4% more theoughput and buy 4% fewer servers or spend way more than 4% less optimizing or whatever and add their 2% optimization and now we are at more than 6%, and the end users can do their business slightly better and so on in a chain that is all of society. Sometimes those gains are mututed. Sometimes that speed turns into error checking, power saving, more throughput, and every trying to do their best to do more with less.
If society was a giant hivemind, then economic viability would take precedence over personal profit. Meanwhile if society is a bunch of isolated individuals, economic viability would take the backseat. So this tells us more about the limits of human psychology than it tells us about economics.