I know one or two people who were or are NEETs in the US. Your family doesn't have to be particularly wealthy to do it, but its not as nice sounding the described self-care lifestyle if you have no money, transportation, friends, etc.

One was from a fairly poor family that lucked into a paid off house in a neighborhood that later gentrified, and just stayed at home with their parents until like age 25 not going out a lot and working only one or two short term jobs from age 18-25. Eventually got a more stable job and then a SO and moved out, but since the main cost of living at home was just feeding themselves, it wasn't a huge financial burden on the parents. The house was a hoard and the parents will probably be in dire straits once they can't live unassisted any more but for now they are stable and could still support a kid or two. A childhood of more significant poverty gave them some skills/habits in terms of living very frugally.

The other I would say was more lower middle class (insofar as that means anything), parents both teachers/artists, had a lot of health issues that resulted in intermittent periods of years living the NEET life throughout their 20s, but eventually got their various conditions under control and finished college and is now looking for a job but can't find anything for the past 6+ months.

But that's going by a more conventional conception of a NEET. Honestly the people "idling" the article mentions are probably more likely young white collar professionals with enough savings to live for 6 months or whatever, or that have rich parents, and aren't desperate enough to take some job that's going to treat them like shit and pay like shit. This is temporary for them, not a sustainable lifestyle.