The idea guy in this scenario doesn't even understand the basic idea that you have to provide "consideration" for the assignment of rights/copyright. If he does

The idea guy in this scenario doesn't even understand the basic idea that you have to provide "consideration" for the assignment of rights/copyright. If he does find a person to build his software as a favor, he's got potential issues like an unjust enrichment claim or worse if he does find a way to monetize it. If I somehow suffer the misfortune of interacting with someone like this I often stop the conversation and tell them to visit Fiverr. A half-baked idea coming from unseasoned people is not even going to make for a good consulting client. I tell them to hire a graphic artist to mock it up before they start with a programmer.