Grocery stores aren't thieves, they're largely pretty terrible businesses with extremely thin margins.
But, to engage with your ridiculous bait and switch: whether I or the thief have $20 is irrelevant to the commerce as he'll presumably spend it at the market too, so even this ridiculously contrived example falls flat on its face.
> rich person bids up Tesla stock and makes Elon into a billionaire off a PE of 317 now, thin air pumped into the balloon in other words with all this money tied up in overpriced TSLA stock than empowering real work in the economy.
Here you go again with some ridiculously biased example, but I'll engage with it for your own sake: money that's invested doesn't just disappear, it goes into the pockets of employees and suppliers or gets reinvested in some other way, continuing the cycle.
> What do you believe the role of government is?
Limited.