Now, fellas, it may not be his fault. Likely, some Know-it-all neighbor who never rode a motorcycle in his life, informed him he had a rare, vintage, collector's bike that was worth a LOT of money. Naturally, he wanted to believe it and there he goes! Just be glad he wasn't told it was worth $10,000.
I ran into this sooo many times, over the years, fooling with antique cars. And, if you attempt to tell him the truth, he thinks you're trying to steal it. It screws up the seller's mind forever!