I had gotten to a point where I had been living paycheck-to-paycheck for about two years, and the company I worked for went bankrupt due to the CEO running away with all of the money that was supposed to be used for our paychecks (yes, really), leaving me jobless and broke.
I wasn't good at saving money, and I got debt collectors coming for back credit card debt, and a lawsuit from my landlord because I wasn't able to pay the rent, all culminating with me bursting into tears at the airport because I realized I didn't have enough credit left on any of my cards to pay for the hotel pre-bill for the interview I was flying to at Amazon.
Fortunately I was able to find another job, and my wife and I set some ground rules about saving money and paying off debts, and since then I've been able to save enough money to have a down payment on a house, and even though I still use credit cards, I treat them like glorified debit cards, and rarely keep the balance higher than $200.
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It's easy to get into an unmanageable cycle of debt when you live paycheck to paycheck; fortunately this happened early enough in my life to where I was able to learn my lessons early enough to keep a buffer of money in case the worst happens. I feel bad for people when this stuff happens, since I wouldn't wish that level of depression on anyone.