This is missing the point. It's not the "mere existence" of the ultra-wealthy, it's that the ultra-wealthy have increasingly been taking all of the economic gains in society. For example: "while the top 10 per cent grew its share of total income by 7.6 per cent between 1980 and 2018 (from 28.5 per cent to 36.1 per cent), the top 1 per cent grew theirs by 6.3 per cent (from 6.8 per cent to 13.1 per cent), which leaves only 1.3 per cent of share growth for the rest of the top 10 per cent."
> The focus really should be on absolute living standards and how to raise them.
That is the focus on the article. The point was that the top 10% are not necessarily raising their absolute living standards, because most of the income gains are going to the top 1%, inflation is rising, housing prices are rising, student loan debt is rising, existence in the top 10% is often only temporary and precarious (think layoffs and other economic trends), and as the article says, "The children of high earners will increasingly see their position depend on, as Maren Toft and Sam Friedman put it, the “bank of mum and dad”, and on what they inherit, rather than only on their professional status."
Someone can easily fall out of the top 10%. It's a lot more difficult to fall out of the top 1% and back into the working class. Wealth begets wealth.