Another interesting aspect to consider is the meaning of "rationality" itself. Often times, you don't know if a behavior is truly rational until enough time has passed to prove it as such. Many things can be rationalized, which is where the trap lies.

For instance, let's say bitcoin ends up being a total fad for some reason in the future, was any participation in bitcoin rational? What would count as rational participation in bitcoin and irrational?

People forget the age-old 'it has to stand the test of time' and I think that applies in a lot of these digital economy cases. Usually, in everyday life, it's easier to judge rationality, as we all have 'life experience' and can make a good, educated judgement as to the outcome people will have if they undertake certain decisions. But for bitcoin, the most we can do is draw parallels to the current fiat economies and gold and whatnot and compare, however it will not be exact as it is a new 'game' on its own.

Time will tell, but I would caution against using 'rational' to describe a lot of the players (even those who vote for the main chain may not be voting out of rational motives).

Interesting topic!