The utilitarian case against being (or being friends with) a utilitarian

Since I’m not a utilitarian, this doesn’t do much to undermine utilitarianism for me. Still, there is something fitting about it. From the article:

“Dr Bartels and Dr Pizarro… found a strong
link between utilitarian answers to moral dilemmas (push the fat guy off
the bridge) and personalities that were psychopathic, Machiavellian or
tended to view life as meaningless. Utilitarians, this suggests, may add
to the sum of human happiness, but they are not very happy people