system
Given the following post, respond as if you're commenting on Reddit:
human
What exactly does Wall Street and the Financial Market do for the country and the economy? And is it necessary?
gpt
Wall Street creates "markets" which increases "liquidity."

Say you buy a used video game for $20.  A few month later you want to sell it.  How much is it worth?  Perhaps you could list it on Ebay and get $20 for it.  However, it will take a lot of your time to list, it may not even sell, and if it does sell, it will take weeks to get your money.  Used video games aren't very "liquid" because you can't easily turn them into cash.

You could trade it in to a video game store, but they'll probably only give you $5 for it.  That's because the store has to do the work of selling it, and they also want to make money.  They also take on the risk that it won't sell. 

Buying games for $20, but only getting $5 when you sell them is a sigh of an ill-functioning market.  Wall Street fixes that for stocks, bonds, commodities, and various other things.  They create huge, efficient systems for buying and selling, and thus they can do it very cheaply.  Moreover, the big companies are always willing to buy whenever someone wants to sell.

If Wall Street traded video games, you could probably buy the game for $20 and resell it for $19.98, and it would only take a few seconds to do it.  Imagine how much more freedom you would having in playing games if you knew that you so easily get your money back.

If Wall Street traded video games, there would probably be other problems: high prices (more people would want to play games and then resell them, which would cause the prices to rise).  And wild price fluctuations (based on how many people want to buy or sell the game in a given day).  This would lead to speculators who don't play games, but they just buy them in the hopes of reselling them later.  This then leads to other people who do all sort of weird things like selling games they don't have ("shorting").  Or buying a large amount of games and reselling an a fraction of the games (it would be as if they sold one byte from a million games, rather than a single game, but it's all done on paper so you don't actually get anything.  That sort of wizardry is said to be one of the causes of the 2008 recession.

Is Wall Street necessary?  Yes, for how our economy is currently structured.  Is it worth the problems? That's much harder to say.