Those lunches could add up to something significant over time. If you're paying $10 per lunch for 10 years, that's $36,500 which is pretty comparable to the cost of a car.

Which is, then, supporting the fact that scale matter, isn't it?

Here the scale of time is larger and does make the 5$ significant, while it isn't at the scale of a few days.

If it takes 1 hour of effort to save 5%:

- Doing 1 hour of effort to save 5% on your $20 lunch is foolhardy for most people. $1/hr is well below US minimum wage. - Doing 1 hour of effort to save 5% on your $50k car is wise. $2500/hr is well above what most people are making at work.

It's not about whether the $2500 affects my ability to buy the car. It's about whether the time it takes me to save that 5% ends up being worthwhile to me given the actual amount saved.

The question is really "given the person-hours it takes to apply the savings, and the real value of the savings, is the savings worth the person-hours spent?"

This is something we often do in our house. We talk about things in terms of hours worked rather than price. I think more people should do it.

By that logic I waste time reading books instead of paying someone else to read them for me.

Paying somebody else to read the book means you don't get the benefit of the book.

Also, this is exactly what you company is doing, paying you to "read the book" so they don't have to.

If you can get the exact same result for less cost (time and money), why not? Things like enjoyment don't factor in since they can't be directly converted into money.

Why do so many people take illustrative examples literally?

I'm sure you can use your imagination to substitute "lunch" and "car" with other examples where the absolute change makes a difference despite the percent change being the same.

Even taking it literally... The 5% might not tip the scale of whether or not I can purchase the car, but I'll spend a few hours of my time comparing prices at different dealers to save $2500. Most people would consider it dumb if you didn't shop around when making a large purchase.

On the other hand, I'm not going to spend a few hours of my time at lunch so that I can save an extra $1 on a meal.

I wouldn't pick 5¢ up off the ground but I would certainly pick up $2500.

You'd keep 5c. A significant number of people who find sums up around $2500 give it back unconditionally, with no expectation of reward. Whoever lost $2500 is having a really bad day.