What I think is missing here is that if anyone thinks that there aren't hedge funds profiting off the inflating the price of Gamestop I have a bridge to sell you. Short selling works like this. First you need margin. Then you need to locate shares to borrow in order to sell. If the shares go down in value you buy back the shares at the lower price and keep the difference. If the shares increase in value you loose money. Potentially a lot. In theory the potential loss on a short position is infinite. So what happened was the hedge fund that sold short received proceeds from the sale. When the stock began to rise the fund began to loose money because short positions have to go through a weekly "Mark to Market" where the proceeds from the sale are adjusted by the market value of the short position. Eventually the shares of gamestop rose such that it likely triggered a margin call where the fund had to either buy to cover (close the short) or increase equity via a deposit cash or securities. The risk to anyone who short sells as opposed to buying long (normal stock buy) is that you can loose way more than your initial investment.
What upset people is that short selling can manipulate the price by keep the price artificially low. What's why in the 2008 crisis there was a ban on short selling financial firms and the instituting of the
"uptick" rule. While I have no love for short sellers it is a legitimate way of making money in the market. However regulators are not wrong for being concerned here. This targeting of Gamestop wrecks havoc in the marketplace by market makers not being able to establish an orderly market, investors getting pinched by trading halts (due to the former). Not to mention the effect it has on pricing options contracts on the stock. I saw put options that had a $112 bid/offer spread this week. That's insane. And make no mistake, it might be retail investors who started this but I guarantee you it will be retail investors that also get hurt.