Often I hear people invoking “my time costs X” argument when discussing ways to save money. Usually that’s how they explain why it does not make sense to spend time to save some amount Y, especially when it is much smaller than what they earn (i.e. X).

They are likely wrong. Let’s see why.

Before we start, I would like to draw your attention to the fact that calculating X is less obvious than it looks. Your work can lead to non-obvious expenses and you may be spending more time on it than you think. For example, you need to commute, perhaps buy business clothes, go somewhere for lunch or even you may be tired in the evening after work. All of these adds up to your 8 hours a days. If you did not working, you wouldn’t have to do all of these, thus, they are caused by your work and should be taken into account when calculating X.

Ok, let’s assume that we trust the number X. I.e. a person works full time (e.g. 40 hours a week) and makes X <some currency> per hour after taking into account all effects of the job on their life. Basically their argument against saving amount Y by spending some time is that they can make amount Y in minutes/hours by working instead.

This is a fallacy because most likely they just can’t work additional hours. I agree that there are various exceptions here like paid overtime (but this is not very sustainable) or freelance. However, often people invoking this argument just work fixed 40 hours a week. That is for them the actual comparison is between “work 40 hours a week + do something instead of saving Y” vs “work 40 hours a week + spend time to save Y”. Thus, from the perspective of getting more money, saving Y > 0 always makes sense. However, this just applies to “saving non-zero amount” in some way, the exact way of doing this may indeed make no sense, due to existence of more efficient ways.

In other words, one should not compare this saving money gig with their work time. It takes your free time instead. After work you can have a rest / spend time with your family / do sports or try to save amount Y.

It is also funny to consider that person’s time is in a way priceless - one will likely have a finite life and there is no way to get any time back. At the same time, by saying “my time costs X” people ignore this fact. Moreover, from this perspective even their working time could be considered wasteful, because they sell their priceless time only for X per hour.

Thus, think twice before saying “my time costs X”. Your time likely costs much more to you, but you should still go forward with that weird way to save money if you feel like it.