That's exactly the point. You can lead a horse to water but you can't make them drink. I sent an email to my entire family regarding the australian royal commission. Even spun it in a positive light to make it more palatable to try and help some wake up. I got nothing but grief over it. Shoot the messenger.
I think Stephen Hassans book escaping cult mind control explains the reasons and best approaches for this quite well. I would be all over letter writing, billboards, phone calls, or whatever other reasonable activism if I thought it would help. Who knows maybe the text I sent is sitting on the back of some of my families heads right now.