It's hard to imagine what an obscene amount of wealth $1 billion is, so Tom Scott demonstrates via travel times. Basically, a tall stack of a million $1 bills laid on its side would take about a minute to walk from end to end. A stack of a billion $1 bills would be a 75-minute car ride from end to end.
There are ways to make the visualization more comparable, like walking both distances or driving both distances at a consistent speed, but the basic idea that a billion is a LOT more than a million is pretty clear.
This one with rice that originally appeared on TikTok also shows a billion, as well as Jeff Bezos' billions:
Image: YouTube / Tom Scott