With friends like that, I hope you don't have many enemies. 

There are dozens of websites with good explanations of "day traders and taxes".  Just do a Google search.  And there are few state rules on what you can do with Lemmings Leaping Cliffs ("everyone else is jumping off the bridge, why won't Mom let me?") -- check for local conditions on LLC's.

However, I suspect one major reason for doing it as an LLC is that transactions can be reported to an EIN, which might be less likely to link to a 1040.  OK, that's just a guess.  I don't have any friends who would explain it to me. 

Here is one basis source. 

https://www.marketwatch.com/story/tax-strategies-for-day-traders-2015-02-25