Get in to medical school, get high grades, get your PhD, be smart, cure AIDS, you'll have more money than you ever want.
Also a lot of dentists have so much money, medicine have really big amount of money inside but a lot of people can't realize it. Your idea about getting rich is really good!
Do note that not everyone CAN become a dentist as it actually requires a lot of investment like paying for tuiton (which is definitely expensive) plus all the materials/equipments needed to set up and a right location to set up your own office (if that's what you are planning to do). The equation in play here is High Investment = High Yield.