Stupidity: Beck wants to kill Peter's friends because they know his secret. Instead of using Edith to attack them directly with a drone strike, or using his illusion technology to lead them into the path of a train like he did with Spider-Man, he instead has a henchman drive them onto a bridge and leave them in the path of his next Elemental attack. Because absolutely nothing is forcing them to stay on the bridge, they all casually walk off the bus and out of immediate danger. It is unfathomable that a man as intelligent and resourceful as Beck would take such an idiotic approach, especially considering all he had at his disposal and how desperate he was.
Stupidity: Assuming that Stark had absolute faith in being able to bring Peter back (otherwise, not much point making a dead person his heir), he had an army of killer drones standing by in space, but he made no use of it during the dramatic battle against Thanos, when you'd expect he'd use every resource available.