Your entire comment seems premised on the mistaken assumption that every self checkout system is implemented in the exact same way.
I use self checkout at certain stores, and avoid it at others.
And the store that this whole post is about, Wal-Mart, is definitely one of the stores I’ll avoid self checkout at. Their system sucks.
Yes. Cash reserves are like unused RAM to me: I have it, so I might as well put it to work. If it turns out I need it somewhere else, I can always go rearrange things to make that possible.
Realistically, I think I’m rich because my wife and I both have strong ability to command high salaries, switch jobs, etc., even in a pretty severe downturn. The main things that might tank the value of that expected future cash flow are disability or death, and we at least insure against those.
We also only need one of our two incomes to support our lifestyle, so we have a certain resilience that just comes from having that buffer. At our current ages, we also already have substantial retirement savings, so we have some resilience there, too.