Try not to waste your time trying to convince someone to try SFI. It would be better to just keep on moving forward to the next person.
You could give them a TC Gift Card and just ask them to check it out for themselves.
You could give them a X-Card and just ask them to check it out for themselves.
You could share with them some of the Testimonials from other SFI affiliates.
https://www.sfimg.com/saying.html
You could share with them all of the training that is available and all of the support that is available and how there are so many other affiliates willing to help anyone.
Best of all you could share with them your every own successful experiences about SFI that you enjoy or have learned.
Trying to convince someone to sign up might become more frustrating for you than for the person that you are trying to convince. It might just be better to say thank you and leave them the information and just keep on moving to the next person.