If there are 5 apples in the world, but I can go to the market and sell 10 of them, that market does not reflect the real price of apples.
Even more so if after that I can pretend to sell apples at even lower prices back and forth between me and my mate, who's also been selling apples.
And that’s before we get to the fact that the markets are rigged against short sellers (e.g., there are circuit breakers that pause trading activity when prices are plummeting. There is no such circuit breaker when prices are rising steeply). There’s also massive information transparency issues. Pretty much everyone who is charged with making private company information public has extremely significant financial incentives to skew that information to be as positive as possible.
Sure, you can hold some stock to hurt some "them"s, but at the same time, you will help other "them"s.