Student loans, man. I escaped without any myself (some good luck on the scholarship/grant front). But I've been helping my husband pay his for almost 20 years now and he still doesn't "own" his master's degree. We spent last night helping our eldest (age 23, 1 year out of college) refinance to get a better interest rate and a monthly payment she can make without starving. I don't look forward to going through this again in two years for the youngest.
@Samanthabwriter oof, I feel that.
I wound up folding my own loans into a mortgage re-fi like 8 years ago. That was a huge win interest-rate-wise. Probably not so much nowadays...