What are you on about? If you own all the shares of a company, you own the company, that's how hostile takeovers can happen. Usually shares come with voting rights, dividends (share of profits) etc. You're right about the price speculation though.

> Also, in the limit, if you owned all the stock in the world, you have destroyed the stock market

Dead wrong, and indeed that is the difference to crypto.

If you own all Bitcoins in the world, it is worth nothing and your net worth is zero. If you own all stocks in the world, you can direct all of those public companies to pay a large chunk of their profit to you every month in dividends, and make those companies do whatever you want them to do (research a way to build a Mars colony, or build better fusion reactors or pay off politicians to do your bidding), which is real power and real wealth.

You are missing the emphasis on the market in stock market. By buying all the stocks of a company, you are basically taking company private – you own the company but the market for its stock is gone – and the value of what you own is the book-value of the business and access to its free cashflow. You don't own an instrument that gets you multiples on that anymore. Stock market gives you a multiple on the book value.

For example, if Elon Musk owned all of Tesla he would have access to $3.7B of its annual free cash-flow or $3.3B of net income. He won't be able to afford to buy Twitter with that. But because he has Tesla stocks which gets a huge multiple on those metrics, he can pledge a fraction of his fraction of ownership in Tesla to get a huge loan with which he is able to buy Twitter (and still enjoy his ownership rights of Tesla stocks!). That's because of stock market.