I mentioned how easy it is to make money in rivals in the other threads. BUT you have to sand bag the events. If you want to make money then dont ever run your best time right away. Pick a slow rival and if you are beating that rival, hit your brakes at the end. Keep doing this and slowly climb up the leaderboards. The key is to pick people NOT on your friends list. Hit the X button and pick "near me" then pick someone just barely faster than you. Beat that person and keep doing this.
Yes there is a drag event in the Monthly event. Third one from the left. THATS where you can make 1 million dollars in about 45 minutes if you do it right. Because each run is only about 10-12 seconds long. So you just keep picking people barely faster than you. If you are ahead of them hit your brakes at the finish line.
Even in other rival modes where you are running laps. If you are ahead of your rival, hit your brakes at the end. Its callled "sandbagging". I have already made well over 20 million in this game and most of that has been from rivals mode.
The drag racing event is by far the easiest way to make money in rivals mode. But you have to sandbag it a lot. If you run your fastest lap right away you will ruin your opportunity to make serious money.