> I realize I waste a lot of time in supermarkets, shops or online stores, browsing/walking around and comparing prices just to penny pinch on low value things, when the savings I would make would have no meaningful impact on my yearly net worth, but the time and mental energy wasted browsing/walking around comparing prices could have better return on investment if used on other things like learning a new skill, reading a book, etc.

That's a feeling I know well. It's even more irrational when it's a habit inherited from parents who weren't particularly poor, so you grow up living in quite a nice house that a lot of time and money has been spent extending, but a 50p ice cream is considered decadent. And after you've made a whole bunch of career choices not optimising for income, saved loads without investing it well, you still find yourself avoiding buying icecreams or coffees when out unless you've got company and comparing cheese prices per kg in a cheap supermarket, not because it's necessary or because you aren't aware that negotiating the price of your next house will save you more than three lifetimes of cheese price comparisons, but simply because doing anything else feels like being ripped off.