Be relentlessly annoying
If you see a person walking toward the edge of a cliff while wearing a blindfold, should you say anything to them?
If they don't react the first time, should you continue to say something?
Is this "harping on it"?
Well, people who continue to archate or support those who do are walking straight toward a cliff, wearing a blindfold, in the dark. If they notice your warnings, they usually just get angry and want the noise to stop. They are on a determined path, and nothing is going to stop the vast majority of them. But, occasionally, you get through to one individual who will stop, take off the blindfold, and try to find a light.
That's what keeps me going, in spite of the anger of the majority who deny the existence of the cliff.
While this is true, there are any number of earnest believers, urgently warning of all sorts of nightmare scenarios.
Better to appeal to their sense of fairness and innate love of freedom and ask them to let you off the train. "I'm not trying to take anything from you, I'm just begging to be free, myself" is a better trigger.