The rule for every conversation
Skepticism about crypto is reasonable, and you will not argue anyone out of it. Do not try. Give short, checkable answers and let the paperwork do the work. You are not selling crypto. You are presenting a cash offer with verified funds.
Be plain about where the money comes from. If someone asks whether the funds are crypto, say yes, and say what happens next: verified, converted, wired. An agent who dodges the question invites exactly the suspicion they were trying to avoid.