It's like saying: I can jump on the field at a Yankee game and "control" 50k spectators and 50m viewers. You may influence them for about a second, but the farther you try to bring the situation from the market's desire, the quicker you'll be corrected.
Sinking 1b into selling apple short would make a small, temporary dent in their market cap.
If you think something is overvalued, you should sell it short. If you think ycombinator companies are overvalued, you should contact the investors and give them odds against the ycombinator startups successes, and it would be in their best interest to take you up on it as a hedge.
In general terms, if you claim to have knowledge of a mispriced asset, there always is an implied economic action you should take to make money off of your unique knowledge.