(Preemptively: for almost that entire time, my family was living basically paycheck-to-paycheck, and our largest expenses were rent and food).
People do leave college and rack up enormous credit card debt. The reason everyone doesn't BK is that there's a social stigma to it, and also, in general, the average American consumer does not have a good idea how the credit system works. Read Patrick McKenzie about this sometime. If more people understood how generous our creditor/debitor laws were to consumers, or how clownshoes disorganized consumer finance was (why would they give a shit? they're judged almost entirely on growth), people would take much more ruthless advantage of it.
But there's also a difference between accumulating $50,000 of revolving credit debt over a span of 5-10 years and six figures based on a decision you make when you are eighteen years old.