People go under on credit cards because they can't stomach the ascetic lifestyles their (newly worsened) financial situations demand, and credit lets them hold on to their standard of living a little while longer.

I don't think better education about how badly it harms them would help much. We see present upside much more strongly than long-term future downside (see: procrastination), even if we are familiar with the nature of that downside.

Emergency funds probably would.