Most people who default on their student loans do so because they either:
1. Aren't currently able to pay it back
2. Weren't able to finish school
It's rare that someone would default on a small loan just because they don't want to pay it back. The accumulation of interest, plus the Government's blatant disregard to individuals who want to work out a payment plan leads to more interest, and people unable to finish their education because they are being told they have to pay off their loan before they can borrow money. The added interest to that loan makes it harder to pay back, and therefore some people may not be able to finish college and acquire good paying jobs.