A few points --
First, this "to be wealthy" thing is an über-oversimplification by Sergei Ganin of what it means for a type to have
as 6th function or hidden agenda. A desire to be wealthy is one of its manifestations; it's not the only one, and not necessarily even the main one.
Second, the hidden agenda is not "nourished", in the way you imply, by the duals - and certainly not if you take those minimalist descriptions.
Third, certainly an ENFj is not, typically, waiting for someone else to give them money. ENFjs are not beggars - not all of them, anyway
Finally, the way it does work is this -- a typical ENFj-ISTj dual pair will put some emphasis on longer-term accumulation of wealth over shorter-term enjoyment of it. In doing that together, the ENFj provides the ISTj with
stimuli and a
reassurance of the way things are going. The ISTj provides the ENFj with a
sense of logical consistency and certainty of understanding, and a
push to actually get things going.