He told me he heard bitcoin could make him to become very rich at the shortest possible time.
This is a sign that he knows little regarding Bitcoin. Yes there is a possibility that Bitcoin can make you very rich at the shortest time but on the other hand, it can make you poor to in a short time. He just heard it to another people who has little to no knowledge too regarding Bitcoin and they don't know how it moves.He was willing to offer me money since I have a physical office where I sell bible/Christian literature. I objected him, but took out time to educate him about bitcoin and the blockchain technology how it's possible for it to change his financial fortune with proper coaching and a determined heart of discipline. He was very concern about who will buy the bitcoin from him and if his fund will be trapped, I showed him the bitcoin market capitalization and he jerked in surprise, and talked little about custodian and non-custodian wallet. He was fascinated and at this point he is more willing to underdsatnd the market than just investing without knowledge.
This is the correct move that you did and make it double because you taught him and give him some information on what truly Bitcoin is and what are the basics of it. Sharing knowledge to people who is passionate to learn Bitcoin is the best decision a person can ever make to his life 
. Proud of you 
Our little exposition of bitcoin and its working principles can help save innocent investors from Ponzi and scam promoters. I never had such opportunity 3years ago, had to read online.
Yeah with your conversation, you've prevented a possible investor from being scammed. He is lucky that he knows you and because of you, he know even the basics of it and to prevent him from getting scammed. It is ok if you got scammed. Learn from your mistakes and share it to others .