(I find this discussion rather amusing, by the way!)
1. The parsing of what the author meant by 'bare minimum' is silly. It's rather obvious that the author isn't approaching the definition the way that, say, the US poverty line is defined, but a threshhold for an 'acceptable' level of comfort FOR THE AUTHOR. That probably means having a car or paying for taxis / zipcars, buying prepared foods not buying in bulk, having home entertainment options like cable TV and good internet, living in an unshared, 'class A'-type residence, etc. It's great that some of us have modified our hedonic tone to not 'need' some or all of these things, but that's besides the point.
2. The current median rent for a 1BR in Baltimore, a typical non-HCOL city, is $1188/mo. (Yes, one can find a cheaper (e.g. studio) apartment, or share an apartment - folks even used to use the 'hot-bed method' where two or three folks would share the same bed but use it in shifts to match their work schedules - but most Americans might, I believe, not consider those as providing an 'acceptable level of comfort.'
Healthcare is now on the order of $850/month if you don't get it through your employer or the ACA.
Transportation costs are upwards of $325/month (buying a $20,000 car once every 15 years is $110/mo., insurance $80, gas $40, maintenance/registration/licensing $80, occasional taxis-buses-subways $15).
Utilities including internet (50), phone (50), electricity (50), TV and streaming video (50) comes to $200/mo.
Per Gallup, the typical American spends about $300/mo on food.
The above costs add to $2863/month. If you add in $250/mo. for travel, $400/mo. for all entertainment [including newspapers & books, dining out (including lunches out, Starbucks etc.), and movies/plays/concerts], $200 for housecleaning, $100 for gifts, $100 for charity, $10 for clothing, and $100 for miscellaneous, that brings you to $4023 which to me is close enough to $4k not to quibble.
2a. While there are certainly ways that one can economize in the budget put forward above, it's hard for me to see how it is 'absurdly luxurious.' Perhaps when one compares it to spending of the typical African or Asian, but not to spending in a developed nation.
3. I live in a HCOL city (DC) and find myself spending around $7-8K/mo. The extra $4K/mo is broken down into: extra rent $2K/mo, extra travel $750/mo, extra entertainment $600/mo., 'toys [electronics like new PCs] $400/mo, add'l. charity $250/mo.
4. Since I don't have childcare expenses, I don't think I could spend more than $10K/mo without it actually becoming work to figure out how to spend it. I don't like first class travel (the people who use it generally annoy me), don't want a Lamborghini, don't want to go clubbing several times a week, don't hire prostitutes or consume expensive drugs, and don't want a full-time staff.
4a. When I first started working 37 years ago, I was told that the top people in what was then my profession made $70,000 a year. I remember thinking at the time 'I would never need more than that! That would be a super luxurious lifestyle.' In current dollars, that would be $189,000 which corresponds to a take-home pay after taxes of about $124,000- or about $10K/month. It's comforting to see that, despite my having much more income than I did back then, my hedonic tone is about the same!