You own more than a quarter of the world using the same rhetoric. They include people with negative wealth in the bottom half, you don't have to go that low until the total sum of everyone there starts going negative.
In countries with the concept of welfare and bankruptcy, "negative wealth" is impossible. Even 0 wealth is impossible because there is a value to the welfare cashflow that the person is eligible for.
Right - a fresh out of med school graduate is worth negative a lot, due to debt, but has great earning potential over their lifetime.
I think this is a confounding factor in national analysis of income, but can't see it being much of a factor in global wealth terms.
Depends quite a lot of what the "own" means and what "half the world" means.
If we are talking about stocks, it might be meaningless, if real-estate, land and so on it is way too much.
Owning stock earns you money, which is very tangible. It is money taken from the labour of workers, and thus not going to them, and is the main way already rich non-working people can still buy whatever they want. It is far from meaningless.