Every racers want to land at least in the top three position since they know that is where the big bucks is. Aside from the prize money, they are also getting some sponsor. Well, the sponsor part is not sure, but that is when bi companies takes notice of them and that is where the big money is. However, in an illegal race, there is only the first place since you need to make a bet to enter the competition and only the winner takes all the money.
This game is just like that as you need to be first place to be able to proceed to the next level. If you can't do that, then you need to repeat that level again.