Well, yeah, money isn't the only motivator for going into dentistry, but it is one. That, and the possibility of a working only 4 days a week after establishing a good practice. There are other careers which offer similar salaries, stability, work-life balance (actuary, pharmacist, podiatrist, etc.), but I've found dentistry to be more interesting than those.
Apart from that, I've considered careers such as teaching high school or becoming a veterinarian, but, like I said, money is one motivator and neither of those careers are particularly well-paid.
As for the people saying just major in finance, there are very few jobs available in investment-banking. And if I was working 80 hour weeks as an investment banker, I'd rarely, if ever, have the time to spend with my family.