Debt to me is just something that buys time by making things immediately available. I think it's healthy only if it supports real growth. For a person, if they need money now to buy an education, home, or other thing that will be put to productive use, debt is valuable they don't need to save up for years at a less productive state first. Same for companies -- 'responsible' debt can unlock growth by meeting obvious and pressing demand today. The future is unclear, so this is of course riddled with traps and competitive pressures, but at least there is a chance that money today rather than tomorrow is a good thing, if your returns can beat the interest rate you pay.

The more predatory side of taking on excessive debt, because one's back is against the wall or one wants to make an impulse purchase, gives you very little additional time (e.g. weeks or months instead of years). This kind of debt is dangerous.