One line does the job: "I close crypto-funded purchases. Your funds are verified, the offer goes in as cash, and the seller gets dollars."
Keep it plain and specific. Leave out price predictions, investment opinions and any attempt to sound like an insider. A buyer with real money in crypto has reason to be private about it, and after a year of being pitched by everyone, they can smell enthusiasm. Be the agent who is competent and discreet.
The second sentence that wins these buyers is about protection: "Before we look at anything, we verify the funds. It takes fifteen minutes, your crypto doesn't move, and it means your offer is taken seriously." A real holder hears that as respect for their time. A victim hears it as the first honest thing anyone has said to them in months.