Empathetically express three ideas.
1) Payoff space vs Risk profile along the sigmoid dose-response ala @paulportesi
2) Reduction in variance ala @rorysutherland
3) Frame the convo to escape the Kobayashi Maru ala @mdvex
1) Paint a vision to take their business past its current understanding. Explain the risks as long the way and show them you're in it with them.
2) People are afraid of getting a bad solution far more than they are of hoping for a good one.