Yet another reason …

… Why I Hate Economists - Washington Free Beacon. (Ht tip, Dave Lull)

Homo economicus is as much a fiction as "capitalism" is.  People engage in commerce, and have done so for untold generations. Karl Marx comes along and calls this practice "capitalism," as if people first had to subscribe to some theory behind it before engaging in its practice. An intellectual's typical bassackwards approach. Aquinas defined truth as the conformity of the mind to the nature of thing itself. For intellectuals, truth is the conformity of the thing itself to their ideas about it.
I like ideas as much as anybody. They can be very useful in discourse. But they are derived from reality. They do not determine reality.