Vlad Tenev, CEO of Robinhood, had an interview with the owner of Barstool Sports a few days ago. He said that after investigating buy/sell orders data from various Market Makers, they determined that the majority of retail were selling and it was the institutions that were doing most of the buying that shot the price over the moon. I do think Reddit got the ball rolling, but I think the institutions got on board as soon as they saw an opportunity for quick profits and it went from there.