The man credited with igniting the 2021 meme stock rally has posted his first social media message in nearly three years.Updated 11:40 AM EDTGameStop  (GME)  shares soared in early Monday trading, taking the stock to the highest levels since last July, after a retail investor who was credited with sparking the 2021 meme-stock frenzy reemerged.The stock was halted from trading by officials on the New York Stock Exchange on five separate occasions in early trading due to surging volatility.Keith G...