Why risk if you arent' ready for consequences

P.S by the way where did he take those money from?

Although Brewster initially believed Robinhood had improperly granted Kearns vast amounts of leverage to trade with, he no longer believes that was the problem. Twitter users who saw Brewster's stream of tweets alerted him that options traders on Robinhood sometimes see a negative cash balance until the other half of their trades are executed.
In other words, Kearns did not actually owe $730,000. But he was apparently led to believe he did.