Actually, these parents are so alert to their children that I think they have spotted this problem before it has had a chance to take root. What is feeding the wants is exposure. Just like us walking through the store and seeing something and wanting it, so this boy is seeing toys and wanting them. Remove the catalogue and the wants will most likely disappear too.
I really don’t think making a request of I child with words, “I want you to”.. would feed the wants. A change in terms could be made if these parents thought it was warranted. “I need you to”… is perhaps a more accurate phrasing. The change from “want” to “need” could also feed the fact that the child is a needed part of the smooth running of the family.
Lastly, there is no need to squelch the “when I am a man” dreaming. It is a good thing for a boy to be talking of his man days. Instead of telling him he can’t have all that large equipment, encourage him to work hard now to learn how to drive and use all of those machines. Praise his desire to have the skills to do the work those tools allow. Encourage a communal heart that doesn’t need to own each machine himself but can lend and borrow with neighbors. Allow boys to dream. As they mature more guidance can be given for the need to save money and pick and choose what is really needed, but that will come soon enough.