no one in my family is a dentist, so i had pretty much no exposure to it and all through high school i thought i wanted to be a doctor (just like about 75% of my class, lol!). all through high school i volunteered at a hospital but the thing i realized was that when patients left, they thanked the nurses, not the doctors, since the doctors didn't really have relationships with them. i realized that i wanted a profession where i was helping people and involved in the health sciences but where i had a chance to really get to know my patients and interact with them. i also love working with my hands - i sculpt and play piano and have always tinkered/fiddled with things, and the more i learned about dentistry the more i realized i loved it!
i'm sure a lot of other people on the forum can also attest to the perks of the job security and private practice aspects of dentistry.
i think everyone has really different reasons for wanting to be a dentist, but i'd say the best thing to do is shadow a bunch of different dentists to see if you fall in love with it - i did!
good luck!