Psychics or Supernatural ability users discard absolute sense of the world, and disregard such questions or rules to enforce their powers.
They possess outright dominion over aspects of reality.
If they wanted fire to burn, fire would burn. No questions asked.
They simply willed it, and it was.
The mysterious symbols etched onto the white gloves of his hands glowed in radiance as his hands fell through the air. Don swiped forward and unleashed almost invisible slashes of wind, like jet pressure.
He simply thought it and the wind bent to his dominion and bacame near invisible blades to strike down his enemy.
They needed the water from the groups, but Barns looked like a troublesome individual. If they couldn't get the water, Don rationally thought it was better to eliminate the dangerous competition anyway
That was why he struck with the intent to kill.