The reality is that oftentimes they simply can't, at least according to a responsible definition of "afford".
All we see from the outside is the brand new Jeep, we don't see the fact that they're underwater on a 72 month loan with 6% interest. The average car loan term in 2019 was 69 months, that's insane. Something like 30% of trade ins have negative equity.
Even ignoring debt, I've spoken to a surprising number of people who make great money and live lavishly but have effectively no retirement savings. The level of financial literacy in the US is abysmal.