Wages, cost of living, and inflation was much lower. $100 back then is like $10,000 now, still peanuts compared to hundreds of thousands of dollars of debt now.
To give you some perspective, let's say the average blue collar worker - a carpenter make $20.24/hr and makes approximately $46,780 a year.
http://www.bls.gov/oes/current/oes472031.htm Average yearly dental school tuition is around $50-60k a year.
Back in the late 1800s, a carpenter made between $0.18 - $0.41 /hr. Let's split in the middle and optimistically say $0.30/hr.
https://outrunchange.com/2012/06/14/typical-wages-in-1860-through-1890/ If they work 60 hrs a week (since Saturdays were not really "weekends" at the time), they'll make $18/wk. Let's say they take 2 weeks off a year and this is before labor laws and people like Eugene Debs had influence in socialistic policies, they'll have made $900/year. $900 average man salary is 9x more than UPenn D-school tuition, but now the average man salary is smaller than UPenn's $70+k/year tuition.
Summary: $100 was a lot of money back then, but it's not as financially insignificant as people may believe.
