It's one metric. And yes, one of its weak points is that my student loans making me less wealthy than the debt-free homeless person is (of course) not the whole story. But that's one narrow slice.
On the scale of 80 people with billions upon billions vs. half of everyone else, it's hardly a disingenuous statistic.
The only reason to use net-worth for such a statistic is to have demagogic sound bites. Most people have negative or very low self-worth because of totally normal and serviceable debt, regardless of whether they're poor or well off. Net worth, i.e. wealth, ignores future earning potential, which is most people's main asset. Repeating the statistic again doesn't change that.
On a global scale, this is nonsense. The number of people globally who have negligible net worth because they earn less than $10 per day vastly exceeds the number of people who have negligible net worth because they've only just started paying down the mortgage on their McMansion and still have student loan repayments remaining.
The purchasing power of those 80 people isn't going to start looking insignificant if you change the basis for comparison to net wealth plus imputed future income streams.
I disagree. If you take the 3 billion poorest people in the world and properly account for their future earnings, it will certainly exceed the combined expected wealth of these 80 billionaires. You couldn't have anything close to this sensationalist statistic.
Also, global poverty is not the fault of Western riches. It's not something we (Westerners) can do anything about either, except engage in mutually beneficial trade. Most of the world is being held back by bad governance, dictatorships and democracies alike. The West has the only economies of significant size that still have the broad outlines of a true free market system.
And how much of those future earnings will go right back into the pockets of the mega-wealthy through rent and interest payments and profits on goods that they buy from companies owned? Nearly all of it, I'd imagine.
Now you're not talking about wealth, but rather some other measure that is apparently more interesting to you. If you're going to count future earning, you ought at least count future spending as well, which quantity may completely swamp the other. After all wealth includes past spending as well as past earning.
My point is that wealth is not a useful metric. To your point, having surplus wealth on the day of your death is not very useful, especially if your kids don't need it. That's why some people get reverse mortgages, to turn the value of their homes into spending cash during retirement.
On average, no one needs wealth. After all, one can simply work for a wage completely spoken-for, hand-to-mouth, letting the automatic deposits feed the automatic withdrawals, a "good" "professional" corporate "citizen", pulling the traces until the heart stops and the teamster cuts loose the carcass to hitch up the next mule.
However, no human life is average in that respect. Everyone occasionally wants to fix the car, bail mother out of jail, keep the new restaurant open for another month, hire another cook, quit the job, drive to California, or whatever. Some of those variable circumstances can be addressed through insurance, but many cannot. Many of them are more along the lines of "it is my will to do this thing I had not planned on doing, right now."
That stuff, that human stuff? That requires wealth. We can paper that over with "easy" credit, but that's a leaky abstraction, and it really only helps one make the choices that consumers are allowed to make. Just ask a 90yo (hint: probably remembers a particular period of history): wealth is strictly better than credit. That's without even considering transaction costs.
ps. try getting a reverse mortgage without first owning a house...
On the scale of 80 people with billions upon billions vs. half of everyone else, it's hardly a disingenuous statistic.