Most of us hasn't seen a real monster truck. That is rare, since not all of us go out everywhere. Most of these trucks are on the mountain, where there are few people. The only time that you would see a monster truck on the city is when there are stunts that need to be done and that is a rare case even for car stunts.
You probably heard someone saying that there is monster. It might be real or it might not be not. We don't know, so we can't tell. There are a few documented sightings all over the world. One thing is certain, you won't see one if you stay in door all the time. In fact, even those, who goes out regularly have a hard time seeing one because those monster will rarely go out in the open.
In this game, you would see a monster. Not only that, these monster will be driving a monster truck. a race is being held and you need to get at least the third spot to unlock new race. Perform some stunts along the way. Crash some bones and you see your truck running fast. You will earn money after the race and you can use that, to upgrade your truck.