You're absolutely right, it is a valid concern. However, unless you're an international student, have bad credit, or have some kind of unusual/extreme circumstance(s)....financing your dental education is very do-able (through loans, military, scholarships, grants, a combination, etc).
REPAYMENT is the issue, and only you can determine your ability to pay. I would suggest (if you can), to live like a student several years after graduation (or at least until you have a handle on the repayment schedule). Heck, I'm assuming you've done it for this long....what's a couple more going to do? SAVE, SAVE, SAVE.
Yes, USC is VERY expensive.....but you already knew that, since it is your first choice. But my philosophy is, if others can do it, I can too! You should take a similar attitude.
I am matriculating into UOP this July. UOP is just as expensive. So I too am in a similar situation....I know what you're thinking and feeling. Just remember that there is that perverbial "light at the end of the tunnel." If I were you, try not to get too bogged down with the numbers. Focus on getting accepted first....then look at all your options. Again good luck, keep us updated!😀