For example, suppose an engineer who is paid $200k per year can spend a week to implement an optimization that reduces costs by 0.1%. If that is 0.1% of something that costs $50 million per year, then that's not a bad use of time.
Is it not? I don't know. I don't run a multi-million dollar business. So this is an honest question. 0.1% of $50 million is a meagre $50000. If someone is running a business that is spending $50 million per year on something, are they really going to care about a small $50k saving per yera?
Spin it around: is it worth it for a sales person who makes $200k per year to spend a week to land a $50,000 per year contract? I think it potentially is, for the same reason, even if the organization as whole makes hundreds of millions of dollars a year.
The thing is, say it takes me an hour to shave off ten bytes in the final build. Value my time per hour at 200$, and the saving of that ten bytes over a year at Wikipedia scale at a thousand dollars, and even investing five times that amount into yak shaving would still be net profitable.
The problem here is that you've switched from proportional thinking to arithmetic thinking in the middle of the thought.
In most cases, if you started with proportional thinking, you should stick to it.
Example of the fallacy: 0.1% of my salary goes to avocado toast, which might not seem that much, but over ten years, that's a thousand dollars!
The fallacy here lies in the fact that a thousand dollars is insignificant over 10 years, but the statement makes it feel significant by switching from proportional to absolute.
"The avocado toast fallacy"?