Someone asked why we should prefer truthful actions over useful actions when truth is often hated.

I don't think the two are actually at odds if your time preference is low enough. But whenever it appears that what is useful is at odds with what is truthful, (people are jailed or censored or persecuted for telling the truth or for asking certain questions) that is an indication that someone or some thing has divorced societal feedback mechanisms from reality, allowing people to be rewarded for the perpetuation of some sort of fraud or delusion. Societal delusions are always unsustainable in the long run, so this is your signal that the herd is headed for a cliff. If you want to have any hope of living in a sane world, and for your kids & loved ones to be able to do the same, then it is your responsibility to communicate or demonstrate what is true as effectively & efficiently as possible. And I think people often wildly overestimate their ability to be truly happy & enjoy "success" gained by renoucing or denying their own faculties or beliefs.

All the aspects of reality that we refuse to embrace will eventually become demons that haunt us from the shadows.