Who's to say they think they're skimping?
Who's to say that they didn't buy exactly what fulfilled them, and it was only 20% of their take-home pay, so they just shoved the rest of it into investments?
Basically - money certainly matters, but only to a point. Once you're fairly comfortable satisfying your genuine needs (food, clothing, shelter, time) more money isn't really going to change how you feel.
It's a mental trap to assume that happiness can be bought, if only you had a bit more money. It leads to empty, hollow, soulless people.
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> Best way to do it is to buy exactly what will fulfill you
My advice? Buying things will never fulfill you. Real fulfillment isn't about having the next shiny ____.
I'm not saying you shouldn't buy that thing, but you should be doing it with intention - How does this fit into my life? What uses do I have for it? Who will I share it with?
I would say the main two goals would be to: have enough money to work when/on what you want (this could be like 500k), and the long term goal is have enough money to make a bigger impact on a community or even the world (prob like 10 mil - 1 bil).
Best way to do it is to buy exactly what will fulfill you, and not a cent more. Maybe that 3 week trip to ___ will, maybe the expensive dinner won't. Etc.