Keith Gill was an unlikely revolutionary. His T-shirts featured cats in sunglasses, his red headband made him look like a cross between peak-era John McEnroe and Cousin Greg from Succession, and his YouTube videos were long, dry analyses of corporate stocks. But revolutionary is exactly what he unwittingly became at the start of 2021, when his advice to buy shares in the videogame store chain GameStop made fortunes for a ragtag army of small individual investors and helped send a handful of larg