Ok, this has been bothering me since the first Helaine Olen story about 401ks being “not enough.”

The problem is not just a matter of what anyone invested in, but when they’re stuck investing. Even if you are continuously investing, the entry and exit points matter — and problems mount when the timing of a market is incongruous with your life circumstances and the points at which you’re making big spends on fixed costs (like children, a home, etc.)

And when I say life circumstances, think for a minute: take out out a 401(k) loan in 2006, and it feels great at the time. Low interest rates (and you’re paying it back to yourself, or at least that’s the pitch). Everything’s near it’s peak: the housing market’s great, commodity prices are high and people are driving gigantic SUV’s. Why not be a little foolish? And of course, everything sucks for the 5 years that follow.

It’s become de rigeur to bash people for being victims of bubble thinking. That stuff only becomes apparent in hindsight, when people have to do post-mortems on CDO’s and CDS’s and see how a relatively small problem like too much speculation on housing in the Sunbelt gets intensely magnified thanks to exotic derivatives based in Bermuda and traded in Chicago and London.