... a person can always chose to ignore the objective nature of profit, and warp their perception of "profit" in any way they please. If they blow their day playing in the sun, they can tell themselves that really this was quite profitable in some way perceptible only to them.

As long as said day didn’t involve shirking obligations to another, what other perception matters than theirs?

Also, it seems to me that you’re suggesting a sort of rationalizing goes on after the fact; the day progresses, then is gone, and only then does the person make an accounting of it in that objective profit-loss book. Why wouldn’t an individual attend to that balance sheet throughout the day, and if it started slipping into loss-land, make a change then? That seems closer to how I have lived many days ... but then, I think mostly in terms of framing/reframing and reflecting, rather than rationalizing; that term has negative connotations that I don’t think are usually justified.

"Profit", on the other hand, is an objective standard .... To further confuse the issue, humans have dual natures, and what can profit one side will often cause a loss for the other: necessitating some hard choices at times.

I don’t see the need to call in the “dual natures” concept here, nor the utility of doing so. Is it not sufficient for your objective model to say that we have complex natures, which makes trying to calculate profit a very challenging endeavor? We can have competing/interfering goals and desires or fears, and quite often do. I posit that only those individuals who are trying to live partly for themselves and for some other(s) truly have a dual nature—and the nearly-universal unhappy results serve as a testament to the wisdom of that course.

Outside of the monetary realm, what is an objective standard by which one can compute profit? To be as clear as I can, I mean “objective” in the “unbiased, impersonal, fact-based” sense of the term.