What if a multi-billionaire organisation were to buy a large amount of bitcoin (for example 30%) only to destroy the private key associated to the wallet and brag about it all over the internet ?
First, would it be possible to prove the loss of the private key ? no
Second, How the market would react ?
First of all, nobody would ever do that. This scenario is wildly imaginative and completely detached from reality.
Second of all, the price of btc would go up. Eliminating Bitcoin means supply is lower, which pushes price higher.