By Dan Weil But Wood’s flagship Ark Innovation ETF has tumbled 63% so far this year, dropping 78% from its February 2021 peak. Cathie Wood’s exchange-traded funds (ETFs) may have hit the skids, but she has crushed it on bitcoin. The Ark Investment Management CEO bought $100,000 worth of bitcoin when it traded at $250, she told The What Bitcoin Did Podcast. As of Oct. 24 that would be worth $7.7 million. Wood bought on the influence of research by her mentor Arthur Laffer, a former economics professor and key economic official in the Reagan administration. Turning to Wood’s Ark ETFs, their perf…