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.
Everyone wants to be rich of course and it is not that easy to be rich because it needs some hard work and also some luck otherwise you will be not be there.
You can even be born rich if your parents are rich or you must make a nice investment so you can make later more profit with it, but that can be risky also.
Just have a daily job and save your money so you can make later a big investment or something.