The coin stood strong precisely when many others collapsed.Flash crashes are like pop quizzes for investors in the sense that they're uncomfortable, revealing, and an opportunity to succeed for those who are prepared. In that vein, the crypto market just got one of the roughest surprise exams in its history, with its worst-ever flash crash on Oct. 10. That brought on a hurricane of uncontrolled selling and forced unwinding of leverage that buckled some of the foundations of the crypto-financial system.Amid ...