Speaking as somebody who currently occupies a comfortable position well within “the 10%”, but grew up in a struggling middle class family (Dad made plenty of money, but Mom and Dad were terrible at managing it): You never fully get over it.
My current paycheck is roughly $1/minute, pre-tax, in salary. My wife makes less, but she’s in the same general line of work. Yeah, it’s a lot by any reasonable standard.
You’d think with a paycheck like that I wouldn’t give a second thought to buying anything less than $100 or so. Yet when I go grocery shopping, I still stock up on canned goods when they are on sale. I wonder if the bargain brand of bacon is acceptable, or if I should splurge on the Hormel. (Answer (after I got the bargain bacon, saving $2): No. It’s terribly salty.) Do I get $25 polo shirt or the $17 one?
I’m not a miser, but I retain a natural thriftiness brought up by wanting to never manage money as poorly as my parents did. (Ironically, they were pretty thrifty on small-time stuff, but were terrible when it came to the bigger picture.)