Look at them... Leaning out of the windows, so eager. They can't wait to see it. They have come for the danger.
Hammond says this in the chapter "Big Rex" while the tour group waits for the tyrannosaurus outside the tyrannosaur paddock. Foreshadowing is one of Crichton's favorite tools: he uses it with bird-dinosaur imagery, with Tina's lizard attack, and again here to foreshadow the novel's major disaster. Just a couple of hours after this scene takes place, the tour group gets stalled outside the same paddock and the tyrannosaurus attacks.
This passage also hints at the inherent problem of resuscitating dinosaurs from extinction. It is reasonable to presume that humans are fascinated with dinosaurs because of the thrill and excitement of imagining predators dozens of times larger than us, capable of snapping any one of us in half in a single motion. As animals like that for the most part do not exist anymore, we understand that a place such as Jurassic Park would appeal to a certain kind of audience that enjoys a good scare now and then. The trill of "danger" the park visitors might be after, however, is undermined and overturned when we see the terrifying reality of the near-death experiences that befall this particular tour group.