What did Tom Sawyer mean when he said in order to make a man or a boy covet a thing it is only necessary to make the thing difficult to attain?

Tom Sawyer's quote suggests that the allure or desire for something increases when it is perceived as challenging to obtain. By making something seem scarce or rare, the value of that item in the eyes of others also increases, leading to a stronger desire to possess it. It exploits the human tendency to desire what is unattainable or considered exclusive.