Student loan debt is anything but a horrible idea. A person graduating high school next month will likely never earn at least $50K (in present value) without a college degree. For the majority of persons with student loan debt, the bulk of it is at low interest rates and all student loan debt is a straight deduction from income (in other words, most persons are getting a 25% discount off their total student debt load).
What's crucial is planning. Some 18-year-olds have no idea the true value of a dollar, go to the university of their favorite football team (out-of-state, of course) borrow the entire cost of attendance and end up owing $200,000+ at graduation. Alternatively, they could've lived with their parents for two years while attending community college and working part-time, transferred to state university and ultimately graduate with a modest amount of debt. Or better yet, attend a commuting school & do internships and graduate with virtually no debt.
The other aspect is paying off debt. When you're 23-year-old making $55,000/year, it's a good idea to pay off as much student loan debt as possible within the first year or two. Instead, many (most?) 23-year-olds make the minimum payment and enjoy the luxuries they dreamed of. These are the people paying student loan debt for 15-20 years. It ain't because the debt was a bad idea, but rather their ability to manage their finances is poor.