Declaring bankruptcy immediately after graduation was last legal in 1976, when private school tuition could be paid for with 20 hours/week of minimum wage labor. Even for an amoral profit optimizer, explicitly planning to have zero assets and maximum debt at graduation and immediately declaring bankruptcy was not yet a particularly compelling idea.

I don't think it'd really be a thing today either, but the circumstances are clearly very different.

Private school tuition at about $1600/year? Public university tuition was well under that, but my recollection is that private university tuition was about double that.

Despite this being true, it's probably bad in the long term to build a society where being honest and trying to do the right thing is a losing strategy.