Lets posit 1929 - in 1929 by most accounts the economy was booming, drive by easy credit and new inventions, a new consumer oriented society was driving buying on credit and speculation in the stock market. But the economy at its core was weak, specifically in the agricultural sector.
Lets Posit today - Uneven recovery from last economic crisis, most of the economy has weak growth, boom of growth in certain markets, weak agricultural commodity pricing.
I see parallels, enough parallels to be concerned really, but not enough to go hide in a hole until its all better. I'm concerned the current administration may not respond full-throatedly enough in the event of a real crisis however.