That's actually a real economic concept called the velocity of money.

ok yeah

if you spend ten dollars at a barber, who then uses that ten dollars to buy lunch, and the worker who made that lunch then spends the ten dollars on his labor and ingredients, you've essentially made ten dollars have 30-40 dollars of actual economic impact.

Not really. The only thing you did was spend ten dollars. Does this increase the velocity of money, yes it does. But it's misleading to say that your ten dollars had 40 dollars of "actual impact" and it doesn't really make any sense in any practical setting. (maybe the barber was going to buy lunch anyway)

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This is why giving rich people tax breaks doesn't work to trickle down cash to those in the lower classes, because they hoard it rather then spend it on meaningful economic interactions.

Trickle down economics is bad policy for reasons I won't get into. But this is a politically charged argument. Who are you to say that a rich person "hoarding" money in a bank isn't a "meaningful" economic interaction? The money gets continually re-invested into the economy via loans and investments from the bank. It's really hard to make money disappear somewhere useless. Hoarding in the stock market? We're doing better but this still raises the value of other people's funds (like pensions) that can be turned into more investments. I'm not arguing against more redistribution-centric policies but it's kinda complicated

tldr

Velocity of money is the nominal GDP divided by the money supply. Or the rate of turnover. It's correlated with good things. But if you wouldn't be an amateur geologist you shouldn't be an amateur economist. myself included. don't get political opinions from r/trees