Maximizing individual payoff is not necessarily contradictory to more intuitive notions of "fairness". One ignored variable is the timescale you're maximizing over. If your company spends money on other things than exec pay, you (and others) are very likely to do better in the long run, in ways that are not mathematically (or computationally) quantifiable, at least by existing theories (or resources). But just because something is not quantifiable does not mean that considering it is "irrational". Rather the opposite, you are using what computational resources you have personally (emotions and intuition) to judge this, rather than ignoring it completely.

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.