I am afraid that they can just easily reject me even without saying all I know about it. Base on my experience, they are not interested in bitcoin, since then, I stopped promoting it to anyone unless they show their interest in front of me.

No, every people in the whole world is in need of money. They might reject this bitcoin promotion since what they prioritize is their need and not to make a profit, especially if they don't know until when they need to wait to have their return of investment.