It's especially necessary when one's circumstances change a lot. It's true for pretty much everyone that the opportunity cost of not using your assets increases as you age - but increasing financial security also changes the calculus in a way which is difficult to unlearn.
Yes, you've hit the nail on the head. I've noticed how people hate paying £9 for what ought to be a £7 lunch. Doesn't seem to matter much if they're fresh out of university, or half way through a high-income career.
I suppose it shifts from being an immediate financial concern, to an old habit, or perhaps a matter of principle.
My theory is that a large amount of 'luxury' commerce is simply giving the customer an excuse not to feel shame, because no longer do they feel a fool, but now they are a special customer with discerning tastes.
I've fallen for that fallacy many times. Only in very few cases does luxury imply higher quality; usually the illusion is formed by the addition of almost worthless decoration (such as folded napkins in a posh restaurant, bought wholesale for literally two a penny).
Can't enjoy a meal because it is overpriced. Or similarly, won't pay $3 for a cold drink in the sun at the beach, since it is $1 in town.
In a completely different direction...
I played skyrim and noticed that I had lots of upgrades, and great equipment and was kind of overpowered.
So, I would go back and play the game naked. (not a new game, just start with the character I had built up)
I would start out with no equipment and just make do with whatever I found. Use the first sword or pants I found and go from there. Kind of fun.