Tesla (TSLA) stock has slumped 11.3% so far this year. Although the stock has gained 2% over the past month, a longtime TSLA shareholder is struggling to maintain faith in Elon Musk's electric vehicle (EV) company, citing a range of issues, as quoted on Yahoo Finance.The Yahoo Finance article indicated that investor and vocal Tesla supporter Gerber recently cut his stake in Tesla from 420,000 shares to 266,000 shares, now valued at around $50 million. Last year, he was a staunch supporter of the company but ...