Was the Greek finance minister pretending to be mad?
No. He was mad. Or utterly incompetent. It doesn't really matter which. Whichever, the Dunning–Kruger effect was in full spate.
Oddly enough, if a bunch of incompetent naifs from a small country with a corrupt political class and a dysfunctional electoral culture promise free sweeties to all to an electorate with a history of wanting and getting free sweeties, get themselves into office, and then attempt to stare down Germany, the EU commission and the IMF with their "game theory" crap, it ends very badly indeed.
Much was made of their finance minister being a professor at the University of Texas.
Firstly, in American universities pretty well everyone on a three-legged (lecturing, teaching, admin) lecturing contract is a professor.
Secondly, Varoufakis wasn't even that, he was a visiting professor: that's someone paid on a per-hour contract to come in and teach a course or collaborate on some research. It isn't in US terms "tenure track" or anything close to it.
Thirdly, University of Texas is a very good university. It's one of the original members of the loose grouping referred to as "public ivy" universities - state-funded institutions such as California, Virginia, Vermont, North Carolina which are approaching the prestige of Ivy League places like Yale and Princeton and the elite non-Ivy private universities like Stanford. But for economics it absolutely isn't Stanford, MIT or Yale (or LSE, Sorbonne...).
So if someone were a visiting lecturer who did a couple of courses at Aston University Business School, would that make you think he was an elite guru who should be trusted with the country's economy on that basis alone?