Selflessness and compassion (at least, for that which occurred from wrong behavior) are common among people who are ignorant of the importance of justice (which may be defined as revealing things as they really are) and the danger of compromising with injustice. Also, in order not to lose all of one's money, one needs to be careful not to be deceived (which requires keeping oneself and acting to serve oneself and the world, rather than selflessness). Are you sure the experiment was able to control for those two issues?