Were you smart, you'd have used your enron stock as the collateral in which case both you and the bank get screwed if the value goes to 0. You default on the loan, you don't have to go bankrupt in this case. Your credit takes a hit for 7 years.

But yeah, if you take out a loan against your home and the housing market collapses and you lose your job (ala 2008) you can end up destitute. The stock market is always a gamble and this doesn't make that better or worse.