The word "irrational" doesn't mean "idiotic", by the way.
Here is an analogy: the business has $150k to spend. Would you rather have it spent on a pair of paintings for the meeting room, or in company-wide renovations? I think it's rational to choose the latter, though it doesn't immediately affect your bottom line.
Ah, I think this explains the disagreement. That kind of "rational" has nothing to do with fairness, and everything to do with maximizing individual payoff. I think you've conflated the two, when they're almost completely incompatible. I knew you were a closet republican ;)
This is why I get supremely annoyed at claims that a specific non-mathematical argument is "irrational".
(Examples of non-computable things: company spends resources on R&D and makes more long-term profit; company spends resources on higher pay for everyone else and boosts morale; reputation of company increases and you attract a wider pool of potential employees; etc.)
In more mathematical terms, greedy optimisation algorithms in the name of short-term "rationality" most often lead you to a local, not global, maximum.
What other people make is definitely not an orthogonal concern, and is hugely relevant. Your justification of not caring about other people earning more is incredibly short-sighted. Yes, it does improve my position if other people earn less, because that money is then available for the company to use on other things, such as paying me.
Furthermore, to suggest that this is "irrational" is offensive and irrational in itself, and would not be inconsistent with psychological propaganda.