In the field of Constitutional Political Economy, analysis often starts from the assumption that "political agents act to fulfill their interest just like everyone else."
But then the analysis immediately assumes that the interest of political actors consists solely of seeking monetary gain. Since most of the people I read working in this area (for instance, this post is inspired by a paper I am currently refereeing in this field) are at least passingly familiar with Austrian economics, this is a somewhat surprising assumption.
One of the things Mises was surely correct about is that "pursuing one's interest," if it is to be a priori true of all agents, must be interpreted extremely broadly. In this sense, as Mises taught us, "one's interest" must include anything that might motivate an agent to act: an aescetic's efforts to abjure all worldly goods, a hero's noble sacrifice of his life for his comrades, and a serial killer's attempts to create as much destruction and suffering as possible, are all examples of agents acting in "their own interest" in this broad sense. Mises was entirely dismissive of the idea that acting in one's own interest could only mean pursuing material gain. And yet, I keep encountering papers that seem to equate the two, from people who I would think ought to know better.
When someone presented a paper at NYU equating "a political agent pursuing his interests" with his "maximizing the revenue he can draw from his position," I offered two notable examples of quite different behavior, and could have offered many more if time had permitted.
My first case was Alexander the Great: if he had merely wanted to maximize the wealth he could extract from his realm, after conquering Persia, he would have simply stopped his campaign, and enjoyed the fabulous wealth of the Persian Empire. But Alexander was obsessed with becoming the greatest warrior-king who had ever existed, and so continued eastward well beyond any point of "revenue maximization."
On the other hand, Ashoka, a king in India, converted to Buddhism (or at least began to support it strongly: there is some historical debate here) after being filled with horror at the deaths resulting from his Kalinga War. In any case, he began to promote Buddhism, erect Buddhist monuments, and do things like use his wealth to establish healthcare facilities for his subjects.
Another obvious counter example would be Hitler: once he had acquired the Rhineland, Austria, Bohemia, and half of Poland, he had a whole lot of territory from which to draw revenue. But his racial obsession would not allow him to stop at that point, leaving him to make decisions that, from a revenue-maximizing point of view, were quite insane.
In Misesian terms, all of three of these rulers were "pursuing their own interest." But the interests that political agents can embrace are no less diverse than those of any other agent.
Now, I have no problem with someone creating a model that assumes political agents are "personal (monetary) revenue maximizing," and seeing what results that model yields. But the papers I have read in this field generally do not do that: they seem to simply assume that what political agents pursue must be gains in material wealth. And I do not see any warrant for that assumption.