A hedge fund bought short position futures contracts for 120% of the available stock on the market. That's the underlying reason the price is going up: because they're forced to somehow buy more than 100% of the available Game Stop stock because they agreed to sell it to the people on the other end of those contracts for a set strike price.
it is ancillary that a short squeeze might be an attendant and inciting event. you could do this with any stock as long as the supply is limited compared to the demand created by the manipulation of trader sentiment. the short squeeze just amplifies the effect
WSB is legally sharing trading information and making informed investing decisions based on public information. What happened with Game Stop is completely predicated on large investors, who should have known better, buying positions that exposed them to an infinite amount of risk.
The short squeeze is the reason this is happening and not "ancillary." The hedge fund took these positions because they thought they were a form a free money. A better analogy would be "The Producers." The audience just walked out of "Spring Time for Hitler" for intermission and they're humming the songs and laughing.