The hedge funds(a corporation that makes its money completely off the stock market), which are generally filled with lots of rich investors, were selling gamestop's stock for really cheap, in order to bankrupt gamestop, and make their other investments more money with the lack of compatition. Then a bunch of people on r/wallstreetbets decided they would all go buy a bunch of gamestop stock to drive it's price up, undoing what the hedge fund was attempting to do(bankrupt gamestop), this means all the money they lost bc they were selling these gamestop stocks below what they were worth, was not going to accomplish anything, meaning all the money the put on bankrupting gamestock was lost. And the stock market being the rigged game it is, the hedge fund quickly used it's power to eliminate ways for the redditors on r/wallstreetbets to buy the stocks, attempting to not lose as much money. I'm pretty sure that's what happened.