I think OP's point to this is that doing that would not be a good business move. I don't believe that in the canonical scenario simply telling the party in question that things are much more complicated than they can possibly imagine and expecting them to accept that is realistic.

I have been a part of projects where first day in discussing the basics of the project the entrepreneur in question has the design "95% complete" which then after the first four hours fluctuates somewhere between 0-20% complete. And all these numbers may as well be randomly chosen for how much of a relation to reality they have at any rate.

Sell them the picks and tents, let them figure it out themselves. When they come back to you with their problems and ask for advice they will finally actually be listening to reason without thinking that their individual case is an exception to the rules and you're just trying to drain their precious equity.