Historic stock market volatility is a blessing in disguise for opportunistic long-term investors.Over the last eight weeks, investors have been taken on quite the ride. The Dow Jones Industrial Average, S&P 500, and Nasdaq Composite have respectively logged some of their largest single-day nominal point gains and declines in their storied histories.While red arrows on Wall Street can be unnerving over short periods, especially to newer investors, they're actually a blessing in disguise. They allow patient i ...