I don't believe you. It is obvious to me that you have never sold enough to experience any slippage.

First, you don't seem to understand how order-book markets work. If you cause the price to drop 12%, then it is you that loses money because you are selling at a 12% lower price.

Then, there is no guarantee that others will "panic sell". The price may even recover immediately, leaving you with a permanent loss.

Finally, when you buy it all back, you cause the price to rise just as it fell when you sold it, and you end up paying a high price, and not a cheap price.

So no, I don't believe what you wrote and I don't believe you are a whale.