[danenania]

It's true in this market, but not true if, for example, the stock market crashes and/or we have a deflationary depression.

Not saying that's particularly likely, but avoiding debt does remove risk in such scenarios--if you never take on debt you can never go bankrupt, even if your upside is also lower. People make different choices about how to balance risk, reduce stress, etc. It only looks irrational when one person imposes their values on the decisions of another.