No jargon really, just maybe my crappy writing.
Imagine like the stock market, when a lot of new money comes in, the market goes up.
(not necessarily all the stocks but as a whole they go up)
When a lot of money leaves, the market (as a whole) goes down
So Bitcoin, similar.
When a shitload of new money comes in, it will (should) go up.
When money is leaving it should go down
And people who short it, most certainly know this and they short when money is leaving, not entering.
(you wanna pee with a hurricane, not into it, lol)