It’s too late to think it through. The alpaca contract will be delisted at five o'clock. After five o'clock, both the long and short positions will be directly liquidated by the exchange (similar to the settlement of contracts in futures trading). Since every long position must correspond to a short position, as long as the main long player is willing to drive the price up, all the short positions become their liquidity at exactly five o'clock, without worrying about being unable to close the positions. Being the main player is just too enjoyable.