Until the possibility is established, many people are going to make fun of, and sideline those working on a solution.

However, I think this thought experiment can bring them to understand that their own beliefs are temporary. If there was a popular movie that followed the plot of how the cure of aging was slowly accepted in society, for example.

Just a short story might be a start.

I think the problem is not that people "support" the idea, but that they are not properly aware of the alternative.