How about this.
Trump receives a guilty verdict by jury in any jurisdiction within the United States AND it is enforced. I.e. stay on appeal doesnt count. If it isnt enforced because he avoids New York or whatever it diesnt count. The bet is about consequences
Every year. You pay me $20 if it has NOT happened. Payment due first of Jan.
When it does happen. I pay you $100.
Death ends the bet.