If Bill Gates takes a fancy to a $100,000 mountain cabin and the owner doesn’t want to sell, he could offer $10 million for it, but that doesn’t increase the market value of the cabin.
Plus, if Bill Gates buys a hours in your neighborhood, it's more or less guaranteed that the prices go up on name recognition alone.
Once the owner accepts that bid, the liquidity in the market has been completely taken, and the likely future market value reverts to ~100,000.
If X is willing to pay Y the value is Y.