That's a lot of money to trust someone to do the bet for you. Why not ask first the people that are close to you? got any friends or relatives where you'll ask them to bet for you.

At that part, you'll get to have a peace of mind. Yes, you'll use an escrow as a guaranteed to this bet. But what will happen is that the escrow will still send the money/btc to the bettor that will do the transaction for you.

How are you going to secure that person will really bet that amount and won't run from you?