To pay back a 100k loan at 4.5% interest (reasonable guess) in 20 years, you've got to pay about 7.5k a year or about 25% of that theoretical person's income. T

To pay back a 100k loan at 4.5% interest (reasonable guess) in 20 years, you've got to pay about 7.5k a year or about 25% of that theoretical person's income. That's a heavy lift. Just doing the math.