Reuters/Yuya ShinoBEIJING (Reuters) - A new breed of small investor is riding China's rollercoaster stock markets, looking for a quick buck and thriving on the volatility that has sent others scurrying to the exit clutching their stomachs. Last summer's 40 percent crash and a 20 percent drop so far in 2016 have sent trading volumes tumbling on the Shanghai and Shenzhen bourses, where retail investors account for 85 percent of the business, unlike more developed markets, where institutions dominate. Many investors have not just been put off by the falls, but by the wild intraday swings, with sharp morning gains frequently swallowed by sharper afternoon losses. Not Zhao De.