I'm thinking at a more fundamental systemic level, not individuals, and the ability to borrow.

Doesn't this quantity of debt indicate that something is severely mispriced relative to its actual cost, necessitating borrowing to "afford" it?
Have governments, or banks, or( insert entity here) distorted the values of some asset, commodity, labor, or service to the point that the only way the imbalance can be rectified is with borrowed money?

I don't buy the theory that it is because we are living beyond our means.  Our means are what we can extract from the earth, then refine, manufacture, transport, and distribute to ourselves. And in recent times, there is a surplus of nearly everything, energy, homes, copper, lumber, grains, electronics, manufactured goods, our consumption is certainly not limited by what we can produce, if prices and unemployment are any indicator.  If one country, or one growing business, or one group of individuals was in debt, then one could argue that they are living beyond their means, or borrowing to invest in productive assets.  But when everyone is in debt, that is not living beyond ones means, that is adapting to the status quo, as it is virtually impossible to build a business, buy a home, or build infrastructure with savings when everyone else is using debt( and therefore inflating , or at least not deflating) those same goods or services, and you must compete with them.  I don't fault the working stiff for being essentially forced to use the system as it is currently.  Frankly, I don't know how someone with a fixed middle class wage is making ends meet at all, let alone to expect them to save up and pay cash for everything.  And the same can be said for governments and businesses, they must compete with all other businesses and governments, who are using debt to finance their growth or programs.

That doesn't make it any more viable.  But doesn't it become a self perpetuating feedback loop?

A couple of comments above, that debt for building productive assets is good debt, which is the position I have used in my life.  But, can even that be sustainable, and is it necessary?  Don't the barriers to entry for starting a business just grow along with the debt available to start?  Does having financing available really allow more people to build and grow a productive asset, or just shift the cost of those assets up a level, but keep the playing field as unlevel as it has ever been.  And just because debt is productive, does it really mean that it is mathematically possible to pay off the interest and the principal?