writes:

The paper legally represents the ownership of the house.

Unless someone else decides to seize it.

In the end the ultimate seller may make a profit or a loss on the sale
of the future, but the future almost never becomes worthless.

For every profit, there is a loss.

In trading futures one can influence the outcome and minimize the risks
by knowing what one is doing.

Famous last words.

In gambling, about the only way to influence the outcome is to count
cards at games like blackjack, which isn't allowed in most casinos.

It works better than playing financial markets.