There are major consequences when the bill comes due on a debt you owe. Personal debt can lead to bankruptcy or foreclosure and the loss of your home.
If paid off before the bill comes due, debt can be a tool. Many communities in North America have utilized the qardh hasanah (goodly loan) as a way to expedite construction projects and then pay people back over time. When businesses fail to pay debt back, they are forced to liquidate and go out of business to satisfy their creditors. In extreme cases, like the economic crisis of a few years ago, major institutions repeatedly utilizing debt as a tool become over-leveraged, creating a rippling collapse.